docs: add contributing guide

Author: js2me

CONTRIBUTING.md

@@ -0,0 +1,8 @@
+# Contributing guide  
+
+1. Fork repository   
+2. Switch to `master` branch
+3. Fix bugs or create features
+4. Use command `pnpm changeset` to describe what you do   
+5. Commit with message using [Conventional commits](https://www.conventionalcommits.org/)  
+6. Open PR!   

README.md

@@ -93,4 +93,8 @@ export const UserBadge = observer(({ userId }: ViewModelPayload<UserBadgeVM>) =>
 
 
 // <UserBadge payload={{ userId: '1' }}>
-```
+```
+
+## Contribution Guide    
+
+Want to contribute ? [Follow this guide](https://github.com/js2me/mobx-tanstack-query/blob/master/CONTRIBUTING.md)