F #3295: Add commit messages guidelines

Hopefully this commit message abides by the rules.

share/doc/dev/COMMIT_MESSAGES.md

@@ -0,0 +1,29 @@
+## Goal
+
+It is extremely important to be able to link changes in the code to specific issues (bugs, features or linting actions). Therefore, commit messages MUST conform to the following rule.
+
+## Commit messages format
+
+# First line
+
+First line of commit messages must have the following structure:
+
+  %{type} #%{issue_number}: %{description}
+
+Where type must be one of the following:
+
+ - revert
+ - F (for new functionality)
+ - B (for bug fixing)
+ - L (for linting)
+ - M (for minor changes with no issue, use the "M #-:" syntax in this case)
+
+Issue number must refer to a GitHub issue of the OpenNebula/one repo
+
+And description needs to be a succinct explanation of the code.
+
+Overall length should be equal or less than 50 characters (this is not enforced)
+
+# Following lines
+
+Remaining text should be wrapped at 72 characters.