Revert "CONTRIBUTING.md: removed commit categories section"

This reverts commit 46739aa601.

CONTRIBUTING.md

@@ -37,7 +37,7 @@ When a pull request is submitted, at least two project participants must conduct
 The commit message should look like this:
 
 ```test
-Commit message header
+[Category] Commit message header
 
 Commit message body, if needed
 ```
@@ -50,6 +50,28 @@ Commit message body, if needed
 
 Maximum number of characters in a commit header is **72** (standard for **Git**). Also, **72** is the maximum length of a line in a commit body.
 
+### Categories
+
+List of existing categories accepted in the project:
+
+- `Krn` - kernel
+- `Drv` - drivers
+- `Libs` - libraries
+- `Apps` - user-space applications
+- `Skins` - skins
+- `Build` - build system
+- `CI/CD` - CI/CD
+- `Docs` - documentation
+- `Data` - images, configs, resources, etc.
+- `All` - global changes
+
+If changes are made to a specific component, the name of the component separated by `/` character needs to be specified. For example:
+
+```text
+Apps/shell
+Libs/libimg
+```
+
 ## Merge commits
 
 > [!WARNING]