Update CONTRIBUTING.md (#828)

CONTRIBUTING.md

@@ -6,9 +6,21 @@ https://docs.aliasvault.net/misc/dev/
 > Tip: if the URL above is not available, the raw doc pages can also be found in the `docs` folder in this repository.
 
 ## Contributing to the documentation
-The docs are built using Jekyll and automatically deploy to GitHub Pages via GitHub Actions. You can build the docs locally by running `docker compose up` in in the `./docs` folder.
+The docs are built using Jekyll and automatically deploy to GitHub Pages via GitHub Actions. You can build the docs locally by running `docker compose up` in the `./docs` folder.
 
 The docs site is based on the open-source template called Just The Docs. Find more information about how this template works in the [official docs](https://just-the-docs.github.io/just-the-docs/).
 
 
 To make changes to the AliasVault documentation please make a PR that directly edits the `docs` markdown files in this repository.
+
+## Contributor License Agreement (CLA)
+Thank you for your interest in contributing to AliasVault (“Project”).
+
+By submitting code, documentation, or other contributions to this Project, you agree to the following:
+
+1. You are legally entitled to grant this license (e.g., you are the author, or have permission).
+2. You grant the Project maintainers a perpetual, worldwide, non-exclusive, royalty-free license to use, modify, distribute, and sublicense your contribution as part of the Project and any derivative works.
+3. You understand that your contribution will be made public and licensed under the same terms as the Project (e.g., AGPLv3), or any later version the maintainers may release.
+4. You are not expected to provide support or warranties for your contribution.
+
+> All contributors must accept the CLA as a condition of contributing. By opening a pull request, you agree to these terms. We may enforce this automatically via GitHub if needed.