doc: clarify .face.icon format requirements (#882)

# Pull Request

## Description

Clarify .face.icon format requirements in documentation

## Type of change

Please put an `x` in the boxes that apply:

- [ ] **Bug fix** (non-breaking change which fixes an issue)
- [ ] **New feature** (non-breaking change which adds functionality)
- [ ] **Breaking change** (fix or feature that would cause existing
functionality to not work as expected)
- [x] **Documentation update** (non-breaking change; modified files are
limited to the documentations)
- [ ] **Technical debt** (a code change that does not fix a bug or add a
feature but makes something clearer for devs)
- [ ] **Other** (provide details below)

## Checklist

Please put an `x` in the boxes that apply:

- [x] I have read the
[CONTRIBUTING](https://github.com/HyDE-Project/HyDE/blob/master/CONTRIBUTING.md)
document.
- [x] My code follows the code style of this project.
- [x] My commit message follows the [commit
guidelines](https://github.com/HyDE-Project/HyDE/blob/master/COMMIT_MESSAGE_GUIDELINES.md).
- [ ] My change requires a change to the documentation.
- [x] I have updated the documentation accordingly.
- [ ] I have added a changelog entry.
- [x] I have added necessary comments/documentation to my code.
- [ ] I have added tests to cover my changes.
- [ ] I have tested my code locally and it works as expected.
- [ ] All new and existing tests passed.

## Screenshots

(if appropriate)

## Additional context

Add any other context about the problem here.

Author: kRHYME7

Configs/.config/hypr/hyprlock.conf

@@ -45,11 +45,15 @@ source = $HOME/.local/share/hyde/hyprlock.conf
 # $MPRIS_IMAGE
 # - The path to the MPRIS image.
 # - If MPRIS is not available, it will show the ~/.face.icon image
+# - For .face.icon to work properly, the image must be in JPEG or PNG format.
+# - To check the file format use: file ~/.face.icon
 # - if available, otherwise, it will show the HyDE logo.
 
 # $PROFILE_IMAGE
 # - The path to the profile image.
 # - If the image is not available, it will show the ~/.face.icon image
+# - For .face.icon to work properly, the image must be in JPEG or PNG format.
+# - To check the file format use: file ~/.face.icon
 # - if available, otherwise, it will show the HyDE logo.
 
 # $GREET_TEXT