docs: in contributing.md include Conventional Commits Specification a…

…nd the `make docs` command (#761)

### Problem

Earlier, I followed the guidelines in
[contributing.md](https://github.com/equinix/terraform-provider-equinix/blob/main/CONTRIBUTING.md)
but [my
PR](#760)
still failed.

### Action

I updated this Doc to include:

1) The [Conventional Commits
Specification](https://www.conventionalcommits.org/en/v1.0.0/)
referenced by job log: Validate PR title (pull_request_target)

2) The `make docs` command referenced by job log: Validate docs
(pull_request)

### Result

This change will inform future contributors, prior to PR, of our
submission specs. This will improve the experience within our Terraform
Provider.

---------

Signed-off-by: Walt Ribeiro <[email protected]>
Signed-off-by: Marques Johansson <[email protected]>
Co-authored-by: Marques Johansson <[email protected]>

CONTRIBUTING.md

@@ -19,8 +19,26 @@ Available via [https://github.com/equinix/terraform-provider-equinix/blob/main/.
 
 Please submit change requests and / or features via [Issues](https://github.com/equinix/terraform-provider-equinix/issues). There's no guarantee it'll be changed, but you never know until you try. We'll try to add comments as soon as possible, though.
 
+## Pull Requests
 All resource and data source changes must be reflected in the documentation, including new attributes and changes to existing attributes. The documentation is generated via `make docs`.  For more detailed instructions for updating docs, see ["Documenting the provider" in the development guide](./DEVELOPMENT.md#documenting-the-provider).
 
+
+## Titles For Pull Requests
+We require pull request titles to follow the [Conventional Commits specification](https://www.conventionalcommits.org/en/v1.0.0/)
+
+Before submitting the PR, please begin your title with one of these available types below:
+ - feat: A new feature
+ - fix: A bug fix
+ - docs: Documentation only changes
+ - style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
+ - refactor: A code change that neither fixes a bug nor adds a feature
+ - perf: A code change that improves performance
+ - test: Adding missing tests or correcting existing tests
+ - build: Changes that affect the build system or external dependencies (example scopes: gulp, broccoli, npm)
+ - ci: Changes to our CI configuration files and scripts (example scopes: Travis, Circle, BrowserStack, SauceLabs)
+ - chore: Other changes that don't modify src or test files
+ - revert: Reverts a previous commit
+
 ## How to Report a Bug
 
 Bugs are problems in code, in the functionality of an application or in its UI design; you can submit them through [Issues](https://github.com/equinix/terraform-provider-equinix/issues) as well.