MONGOID-5082 Create contributing guidelines (#5472)

* MONGOID-5082 Create contributing guidelines

* MONGOID-5082 propose test coverage

* MONGOID-5082 whitespace

* MONGOID-5082 update language

* add intro

Author: neilshweky

source/contributing.txt

@@ -10,3 +10,4 @@ Contributing
   :titlesonly:
 
   contributing/code-documentation
+  contributing/contributing-guidelines

source/contributing/contributing-guidelines.txt

@@ -0,0 +1,43 @@
+.. _contributing-guildelines:
+
+***********************
+Contributing Guidelines
+***********************
+
+.. default-domain:: mongodb
+
+.. contents:: On this page
+   :local:
+   :backlinks: none
+   :depth: 2
+   :class: singlecol
+
+
+Contributing Guidelines
+=======================
+
+If you wish to propose an enhancement to Mongoid, please create a Jira ticket 
+describing the enhancement and what it would enable you to achieve in your 
+application that is not already possible. If you believe Mongoid is not 
+behaving correctly, please create a Jira ticket describing how you use Mongoid,
+what the existing behavior is that you consider incorrect or problematic, and
+what your desired behavior is. If you wish to make changes yourself, the 
+following guildelines should be followed:
+
+#. Create a fork of Mongoid.
+#. Create a new branch in that fork.
+#. Make your changes.
+#. Ensure that the proposed changes have adequate test coverage.
+#. Raise a PR against Mongoid master. If these changes correspond to a specific
+   Jira ticket, title the PR: "MONGOID-<ticket #> Description of Changes".
+#. The Mongoid team will review the PR and make comments/suggest changes.
+#. Once all of the changes and fixes are made, and the Mongoid team determine
+   the PR fit for merging, we will merge the PR into master and determine
+   whether it needs to be backported.
+#. Backports to previous stable versions are done if the change is a bug fix, 
+   is not backwards breaking, and if the commit is applicable to the 
+   corresponding stable branch. Presently backport candidates would include 
+   versions 7.3-8.0.
+#. Changes to 6.0-7.2 are generally not made unless it fixes a security
+   vulnerability.
+#. 5.x and earlier is generally not supported.