📝 docs(contributing): Add commit style guidelines

CONTRIBUTING.md

@@ -3,6 +3,70 @@
 We'd love to accept your patches and contributions to this project. There are
 just a few small guidelines you need to follow.
 
+## Version control
+### Commit style
+To make sure that all our commits remain consistent through time, the project is set up to validate (on Pull Requests)
+that all commits have to the following format:
+
+```bash
+:gitmoji: type(scope?): subject
+body?
+footer?
+```
+
+For that we use [commitlint-config-gitmoji](https://www.npmjs.com/package/commitlint-config-gitmoji)
+as our [commitlint](https://www.npmjs.com/package/commitlint), if you are worried you might write a commit
+using a wrong emoji, make sure have the project node dependencies installed (`npm install`), this will enable
+a pre-commit hook that checks for the correct format before each commit.
+
+If desired, you could also bypass this check by adding the `-n` option at the end of your commit,
+this might be convenient if you just want to try some things out.
+
+```shell
+git commit -m "wrong commit" -n
+```
+
+#### [:gitmoji:](https://gitmoji.dev/) (required)
+Must be a valid emoji code, you could easily find out the correct one by executing
+in your shell:
+
+```shell
+npx gitmoji-cli --search <string>
+```
+
+where `<string>` could be the word "bug" if you are looking for the bug emoji.
+
+#### type (required)
+**Must** be one of the following
+
+```text
+  'feat'           // Introducing new features
+  'fix'            // Fixing a bug
+  'refactor'       // Refactoring code (Not Introducing features or fix)
+  'docs'           // add documents
+  'test'           // Adding unit tests or e2e test
+  'perf'           // Improving performance
+  'revert'         // Reverting changes or commits
+  'style'          // Updating the UI and style files
+  'build'          // build artifacts
+  'ci'             // working about CI build system
+  'wip'            // Work in progress
+  'chore';         // Work with configuration or other stuff
+```
+
+#### scope (optional)
+e.g. Unguard microservices (`like-service`, `membership-service`, etc), `docs`, etc.
+
+#### subject (required)
+**Must** be written following the styles: `Sentence case`, `Start Case` and `PascalCase`.
+
+And use them as you normally would:
+* `Sentence case` for normal sentences
+* `Start Case` for names
+* `PascalCase` for referring to file/class names that have that casing style.
+
+*Note: Acronyms are allowed:* `HTTP`, `SSL`, `DSL`.
+
 ## Contributor License Agreement
 
 Contributions to this project must be accompanied by a Contributor License