4 files changed, 72 insertions, 12 deletions
diff --git a/guides/source/4_1_release_notes.md b/guides/source/4_1_release_notes.md
index 1980f4d4cf..477268f4bc 100644
--- a/guides/source/4_1_release_notes.md
+++ b/guides/source/4_1_release_notes.md
@@ -422,11 +422,6 @@ for detailed changes.
 
 * Deprecated `quoted_locking_column` method, which isn't used anywhere.
 
-* Deprecated the delegation of Array bang methods for associations.
-  To use them, instead first call `#to_a` on the association to access the
-  array to be acted
-  on. ([Pull Request](https://github.com/rails/rails/pull/12129))
-
 * Deprecated `ConnectionAdapters::SchemaStatements#distinct`,
   as it is no longer used by internals. ([Pull Request](https://github.com/rails/rails/pull/10556))
 
@@ -502,6 +497,9 @@ for detailed changes.
 
 * Don't create or drop the test database if RAILS_ENV is specified explicitly.
 
+* `Relation` no longer has mutator methods like `#map!` and `#delete_if`. Convert
+  to an `Array` by calling `#to_a` before using these methods. ([Pull Request](https://github.com/rails/rails/pull/13314))
+
 Active Model
 ------------
 
@@ -585,7 +583,7 @@ for detailed changes.
   [More Details](upgrading_ruby_on_rails.html#changes-in-json-handling))
 
 * Deprecated `ActiveSupport.encode_big_decimal_as_string` option. This feature has
-  been extracetd into the [activesupport-json_encoder](https://github.com/rails/activesupport-json_encoder)
+  been extracted into the [activesupport-json_encoder](https://github.com/rails/activesupport-json_encoder)
   gem.
   ([Pull Request](https://github.com/rails/rails/pull/13060) /
   [More Details](upgrading_ruby_on_rails.html#changes-in-json-handling))
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md
index 3783be50c0..d164b08d93 100644
--- a/guides/source/active_record_querying.md
+++ b/guides/source/active_record_querying.md
@@ -1455,7 +1455,7 @@ If you'd like to use your own SQL to find records in a table you can use `find_b
 ```ruby
 Client.find_by_sql("SELECT * FROM clients
   INNER JOIN orders ON clients.id = orders.client_id
-  ORDER clients.created_at desc")
+  ORDER BY clients.created_at desc")
 ```
 
 `find_by_sql` provides you with a simple way of making custom calls to the database and retrieving instantiated objects.
diff --git a/guides/source/api_documentation_guidelines.md b/guides/source/api_documentation_guidelines.md
index 311cc23cf0..7466b4ff48 100644
--- a/guides/source/api_documentation_guidelines.md
+++ b/guides/source/api_documentation_guidelines.md
@@ -128,6 +128,53 @@ On the other hand, regular comments do not use an arrow:
 #   polymorphic_url(record)  # same as comment_url(record)
 ```
 
+Booleans
+--------
+
+In predicates and flags prefer documenting boolean semantics over exact values.
+
+When "true" or "false" are used as defined in Ruby use regular font. The
+singletons `true` and `false` need fixed-width font. Please avoid terms like
+"truthy", Ruby defines what is true and false in the language, and thus those
+words have a technical meaning and need no substitutes.
+
+As a rule of thumb, do not document singletons unless absolutely necessary. That
+prevents artificial constructs like `!!` or ternaries, allows refactors, and the
+code does not need to rely on the exact values returned by methods being called
+in the implementation.
+
+For example:
+
+```markdown
+`config.action_mailer.perform_deliveries` specifies whether mail will actually be delivered and is true by default
+```
+
+the user does not need to know which is the actual default value of the flag,
+and so we only document its boolean semantics.
+
+An example with a predicate:
+
+```ruby
+# Returns true if the collection is empty.
+#
+# If the collection has been loaded
+# it is equivalent to <tt>collection.size.zero?</tt>. If the
+# collection has not been loaded, it is equivalent to
+# <tt>collection.exists?</tt>. If the collection has not already been
+# loaded and you are going to fetch the records anyway it is better to
+# check <tt>collection.length.zero?</tt>.
+def empty?
+  if loaded?
+    size.zero?
+  else
+    @target.blank? && !scope.exists?
+  end
+end
+```
+
+The API is careful not to commit to any particular value, the predicate has
+predicate semantics, that's enough.
+
 Filenames
 ---------
 
@@ -163,7 +210,10 @@ class Array
 end
 ```
 
-WARNING: Using a pair of `+...+` for fixed-width font only works with **words**; that is: anything matching `\A\w+\z`. For anything else use `<tt>...</tt>`, notably symbols, setters, inline snippets, etc.
+WARNING: Using `+...+` for fixed-width font only works with simple content like
+ordinary method names, symbols, paths (with forward slashes), etc. Please use
+`<tt>...</tt>` for everything else, notably class or module names with a
+namespace as in `<tt>ActiveRecord::Base</tt>`.
 
 ### Regular Font
 
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 4afd0600c4..38f7162fcf 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -386,6 +386,8 @@ encrypted cookies salt value. Defaults to `'signed encrypted cookie'`.
 
     The default setting is `true`, which uses the partial at `/admin/posts/_post.erb`. Setting the value to `false` would render `/posts/_post.erb`, which is the same behavior as rendering from a non-namespaced controller such as `PostsController`.
 
+* `config.action_view.raise_on_missing_translations` determines whether an error should be raised for missing translations
+
 ### Configuring Action Mailer
 
 There are a number of settings available on `config.action_mailer`:
@@ -413,10 +415,18 @@ There are a number of settings available on `config.action_mailer`:
 * `config.action_mailer.default_options` configures Action Mailer defaults. Use to set options like `from` or `reply_to` for every mailer. These default to:
 
     ```ruby
-    :mime_version => "1.0",
-    :charset      => "UTF-8",
-    :content_type => "text/plain",
-    :parts_order  => [ "text/plain", "text/enriched", "text/html" ]
+    mime_version:  "1.0",
+    charset:       "UTF-8",
+    content_type: "text/plain",
+    parts_order:  ["text/plain", "text/enriched", "text/html"]
+    ```
+
+    Assign a hash to set additional options:
+
+    ```ruby
+    config.action_mailer.default_options = {
+      from: "noreply@example.com"
+    }
     ```
 
 * `config.action_mailer.observers` registers observers which will be notified when mail is delivered.
@@ -441,6 +451,8 @@ There are a few configuration options available in Active Support:
 
 * `config.active_support.use_standard_json_time_format` enables or disables serializing dates to ISO 8601 format. Defaults to `true`.
 
+* `config.active_support.time_precision` sets the precision of JSON encoded time values. Defaults to `3`.
+
 * `ActiveSupport::Logger.silencer` is set to `false` to disable the ability to silence logging in a block. The default is `true`.
 
 * `ActiveSupport::Cache::Store.logger` specifies the logger to use within cache store operations.