conditions of contributing have changed (details have been added)

CONTRIBUTING.md

@@ -1,13 +1,24 @@
 # Contributing
 
+![GitHub contributors][contributors]
+
 1. First of all, fork and clone this repository;
 2. Clone your new repository to your system;
-3. Create a new branch;
-4. Commit changes and push the new branch;
-5. Open and submit a PR.
+3. Create a new branch:
 
-![GitHub contributors][contributors]
+   - If adding a new feature:
 
-Feedback, bug reports, and pull requests are welcome. Feel free to ask for help.
+     1. The branch should be named `feature/xxx` (#xxx is the **short** name your feature)
+     2. Add accompanying test case.
+     3. Provide a convincing reason to add this feature.
+
+   - If fixing a bug:
+
+     1. The branch should be named `fix/xxx` (#xxx is the name a bug)
+     2. Provide a detailed description of the bug in the PR. _Live demo preferred._
+     3. If you are resolving a known issue, add `fixes #yyy` (#yyy is the issue id) in your PR title.
+
+4. Commit changes and push the new branch;
+5. Open and submit a PR.
 
 [contributors]: https://img.shields.io/github/contributors/andrejsharapov/vue-box-shadows?color=fd7e17