Clarification for noobs. (#31704)

* Update active_record_basics.md

I made a bit of clarification for people, who are not familiar with SQL (pretty much like me). However, I don't know what tutorial for MySQL is better, so I haven't inserted a link yet.

* [ci skip] For those who new to GitHub

Added more instructions for contributing guides. Without them, it was somewhat confusing for me to find what I should actually do.

* Update active_record_basics.md

Fixed grammar and text wrapping as requested.

* Update contributing_to_ruby_on_rails.md

Revised instructions.

* Update contributing_to_ruby_on_rails.md

Typos

* Update active_record_basics.md

* [ci skip] Update active_record_basics

Added a few links to SQL tutorials found on the net.
Also, changed MySQL to SQL (or one of its extensions) - I think that it's a good compromise.

* [ci skip] I think now it's more clear what to do.

* [ci skip] Fixed strings

[Rafael Mendonça França + loothunter1]

2 files changed, 8 insertions, 4 deletions

diff --git a/guides/source/active_record_basics.md b/guides/source/active_record_basics.md
index 9be9c6c7b7..859679d53a 100644
--- a/guides/source/active_record_basics.md
+++ b/guides/source/active_record_basics.md
@@ -45,6 +45,8 @@ relationships of the objects in an application can be easily stored and
 retrieved from a database without writing SQL statements directly and with less
 overall database access code.
 
+NOTE: If you are not familiar enough with relational database management systems (rDBMS) or structured query language (SQL), please go through [this tutorial](https://www.w3schools.com/sql/default.asp) (or [this one](http://www.sqlcourse.com/)) or study them by other means. Understanding how relational databases work is crucial to understanding Active Records and Rails in general.
+
 ### Active Record as an ORM Framework
 
 Active Record gives us several mechanisms, the most important being the ability
@@ -142,7 +144,7 @@ end
 This will create a `Product` model, mapped to a `products` table at the
 database. By doing this you'll also have the ability to map the columns of each
 row in that table with the attributes of the instances of your model. Suppose
-that the `products` table was created using an SQL statement like:
+that the `products` table was created using a SQL (or one of its extensions) statement like:
 
 ```sql
 CREATE TABLE products (
@@ -152,8 +154,9 @@ CREATE TABLE products (
 );
 ```
 
-Following the table schema above, you would be able to write code like the
-following:
+Schema above declares a table with two columns: `id` and `name`. Each row of
+this table represents a certain product with these two parameters. Thus, you
+would be able to write code like the following:
 
 ```ruby
 p = Product.new
diff --git a/guides/source/contributing_to_ruby_on_rails.md b/guides/source/contributing_to_ruby_on_rails.md
index 967c992c05..c1668f989b 100644
--- a/guides/source/contributing_to_ruby_on_rails.md
+++ b/guides/source/contributing_to_ruby_on_rails.md
@@ -134,7 +134,8 @@ learn about Ruby on Rails, and the API, which serves as a reference.
 
 You can help improve the Rails guides by making them more coherent, consistent or readable, adding missing information, correcting factual errors, fixing typos, or bringing them up to date with the latest edge Rails.
 
-To do so, open a pull request to [Rails](https://github.com/rails/rails) on GitHub.
+To do so, make changes to Rails guides source files (located [here](https://github.com/rails/rails/tree/master/guides/source) on GitHub). Then open a pull request to apply your
+changes to master branch.
 
 When working with documentation, please take into account the [API Documentation Guidelines](api_documentation_guidelines.html) and the [Ruby on Rails Guides Guidelines](ruby_on_rails_guides_guidelines.html).