Added a lot of Oxford commas

[ci skip] A regular expression was used to find a lot of missing Oxford
commas and add them.  The regular expression was as follows.

", ([a-zA-Z0-9.\`:'\"]+ ){1,6}(or|and) "

1 files changed, 8 insertions, 8 deletions

diff --git a/guides/source/form_helpers.md b/guides/source/form_helpers.md
index 53c567727f..0ee64c855e 100644
--- a/guides/source/form_helpers.md
+++ b/guides/source/form_helpers.md
@@ -165,7 +165,7 @@ make it easier for users to click the inputs.
 Other form controls worth mentioning are textareas, password fields,
 hidden fields, search fields, telephone fields, date fields, time fields,
 color fields, datetime-local fields, month fields, week fields,
-URL fields, email fields, number fields and range fields:
+URL fields, email fields, number fields, and range fields:
 
 ```erb
 <%= text_area_tag(:message, "Hi, nice site", size: "24x6") %>
@@ -208,7 +208,7 @@ Output:
 Hidden inputs are not shown to the user but instead hold data like any textual input. Values inside them can be changed with JavaScript.
 
 IMPORTANT: The search, telephone, date, time, color, datetime, datetime-local,
-month, week, URL, email, number and range inputs are HTML5 controls.
+month, week, URL, email, number, and range inputs are HTML5 controls.
 If you require your app to have a consistent experience in older browsers,
 you will need an HTML5 polyfill (provided by CSS and/or JavaScript).
 There is definitely [no shortage of solutions for this](https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills), although a popular tool at the moment is
@@ -442,7 +442,7 @@ output:
 
 Whenever Rails sees that the internal value of an option being generated matches this value, it will add the `selected` attribute to that option.
 
-WARNING: When `:include_blank` or `:prompt` are not present, `:include_blank` is forced true if the select attribute `required` is true, display `size` is one and `multiple` is not true.
+WARNING: When `:include_blank` or `:prompt` are not present, `:include_blank` is forced true if the select attribute `required` is true, display `size` is one, and `multiple` is not true.
 
 You can add arbitrary attributes to the options using hashes:
 
@@ -709,7 +709,7 @@ Understanding Parameter Naming Conventions
 ------------------------------------------
 
 As you've seen in the previous sections, values from forms can be at the top level of the `params` hash or nested in another hash. For example, in a standard `create`
-action for a Person model, `params[:person]` would usually be a hash of all the attributes for the person to create. The `params` hash can also contain arrays, arrays of hashes and so on.
+action for a Person model, `params[:person]` would usually be a hash of all the attributes for the person to create. The `params` hash can also contain arrays, arrays of hashes, and so on.
 
 Fundamentally HTML forms don't know about any sort of structured data, all they generate is name-value pairs, where pairs are just plain strings. The arrays and hashes you see in your application are the result of some parameter naming conventions that Rails uses.
 
@@ -763,7 +763,7 @@ We can mix and match these two concepts. One element of a hash might be an array
 
 This would result in `params[:addresses]` being an array of hashes with keys `line1`, `line2` and `city`. Rails decides to start accumulating values in a new hash whenever it encounters an input name that already exists in the current hash.
 
-There's a restriction, however, while hashes can be nested arbitrarily, only one level of "arrayness" is allowed. Arrays can usually be replaced by hashes; for example, instead of having an array of model objects, one can have a hash of model objects keyed by their id, an array index or some other parameter.
+There's a restriction, however, while hashes can be nested arbitrarily, only one level of "arrayness" is allowed. Arrays can usually be replaced by hashes; for example, instead of having an array of model objects, one can have a hash of model objects keyed by their id, an array index, or some other parameter.
 
 WARNING: Array parameters do not play well with the `check_box` helper. According to the HTML specification unchecked checkboxes submit no value. However it is often convenient for a checkbox to always submit a value. The `check_box` helper fakes this by creating an auxiliary hidden input with the same name. If the checkbox is unchecked only the hidden input is submitted and if it is checked then both are submitted but the value submitted by the checkbox takes precedence. When working with array parameters this duplicate submission will confuse Rails since duplicate input names are how it decides when to start a new array element. It is preferable to either use `check_box_tag` or to use hashes instead of arrays.
 
@@ -823,7 +823,7 @@ will create inputs like
 <input id="person_address_primary_1_city" name="person[address][primary][1][city]" type="text" value="bologna" />
 ```
 
-As a general rule the final input name is the concatenation of the name given to `fields_for`/`form_for`, the index value and the name of the attribute. You can also pass an `:index` option directly to helpers such as `text_field`, but it is usually less repetitive to specify this at the form builder level rather than on individual input controls.
+As a general rule the final input name is the concatenation of the name given to `fields_for`/`form_for`, the index value, and the name of the attribute. You can also pass an `:index` option directly to helpers such as `text_field`, but it is usually less repetitive to specify this at the form builder level rather than on individual input controls.
 
 As a shortcut you can append [] to the name and omit the `:index` option. This is the same as specifying `index: address` so
 
@@ -873,7 +873,7 @@ Or if you don't want to render an `authenticity_token` field:
 Building Complex Forms
 ----------------------
 
-Many apps grow beyond simple forms editing a single object. For example, when creating a `Person` you might want to allow the user to (on the same form) create multiple address records (home, work, etc.). When later editing that person the user should be able to add, remove or amend addresses as necessary.
+Many apps grow beyond simple forms editing a single object. For example, when creating a `Person` you might want to allow the user to (on the same form) create multiple address records (home, work, etc.). When later editing that person the user should be able to add, remove, or amend addresses as necessary.
 
 ### Configuring the Model
 
@@ -890,7 +890,7 @@ class Address < ApplicationRecord
 end
 ```
 
-This creates an `addresses_attributes=` method on `Person` that allows you to create, update and (optionally) destroy addresses.
+This creates an `addresses_attributes=` method on `Person` that allows you to create, update, and (optionally) destroy addresses.
 
 ### Nested Forms