misc: add README

https: //git.jami.net/savoirfairelinux/jami-client-qt/-/issues/1110
Change-Id: I4b4235e98483be423a407a816272827e57b1965d

README.md

+# Plugin Store
+
+The idea is to provide the user a quick way to discover and install plugins via the plugin store.
+
+# Contributing
+
+We have a set of ESLint rules that define clear syntax rules (web/.eslintrc.json). You will need the following tools:
+
+* ESLint (The pluggable linting utility for JavaScript and JSX) https://eslint.org/
+
+We will not accept patches introducing non-ESLint-compliant code.
+
+## Linting via pre-commit hook
+
+Set up the pre-commit hook:
+
+In the root directory of your Git repository, navigate to the `.git/hooks` folder.
+Create or edit the pre-commit file (with no file extension) in that folder.
+
+If you only want to use our pre-commit hook:
+
+```bash
+cp ./extras/scripts/pre-commit.sh .git/hooks/pre-commit
+chmod +x ./git/hooks/pre-commit
+chmod +x .extras/scripts/pre-commit
+```
\ No newline at end of file