chore(extension): add contribution md

apps/browser-extension-wallet/CONTRIBUTING.md

@@ -0,0 +1,8 @@
+# Contributing
+
+1. Please open an [issue](https://github.com/input-output-hk/lace/issues) that would clearly define the problem, or bug you are trying to solve (please use the appropriate template for each). Once complete please open PR as a proposed solution to it.
+2. Ensure that your source branch is up-to-date with the `main` branch, could be built and tested locally, and update proper configuration files with details of changes to the interface, such as added environment variables, changed API endpoints, etc.
+3. Please follow the coding conventions that are mostly enforced by either the root-level TS or lint configs (try to avoid disabling such rules or provide a strong reason behind that).
+4. Please keep in mind that it might take some time till your PR gets properly reviewed and be open for further discussions.
+
+Please see [README.md](https://github.com/input-output-hk/lace#readme) for more info.