Review issue and pull templates, drop unused contributing file

The CONTRIBUTING.md from root dir will be used by github

Author: strk

.github/CONTRIBUTING.md

@@ -1,23 +1,22 @@
-The issue will be closed without any reasons if it does not satisfy any of following requirements:
 
-1. Please speak English, we have forum in [Chinese](https://discuss.gogs.io/c/getting-help/getting-help-chinese).
-2. Please post questions or config/deploy problems on our forum: https://discuss.gogs.io, here are bugs and feature requests only.
+1. Please speak English
+2. Please ask questions or config/deploy problems
+   on our gitter channel: https://gitter.im/go-gitea/gitea
+   Here are bugs and feature requests only.
 3. Please take a moment to search that an issue doesn't already exist.
-4. Please give all relevant information below for bug reports; incomplete details considered invalid report.
+4. Please give all relevant information below for bug reports; incomplete
+   details considered invalid report.
 
-**You MUST delete above content including this line before posting; too lazy to take this action considered invalid report.**
+**You MUST delete above content including this line before posting;
+too lazy to take this action considered invalid report.**
 
-- Gogs version (or commit ref): 
-- Git version: 
-- Operating system: 
+- Gitea version (or commit ref):
+- Git version:
+- Operating system:
 - Database (use `[x]`):
   - [ ] PostgreSQL
   - [ ] MySQL
   - [ ] SQLite
-- Can you reproduce the bug at https://try.gogs.io:
-  - [ ] Yes (provide example URL)
-  - [ ] No
-  - [ ] Not relevant
 - Log gist:
 
 ## Description

.github/ISSUE_TEMPLATE.md

@@ -1,9 +1,10 @@
-The pull request will be closed without any reasons if it does not satisfy any of following requirements:
+Please check the following:
 
-1. Please make sure you are targeting the `develop` branch.
-2. Please read contributing guidelines:
-https://github.com/go-gitea/gitea/wiki/Contributing-Code
-3. Please describe what your pull request does and which issue you're targeting
-4. ... if it is not related to any particular issues, explain why we should not reject your pull request.
+1. Make sure you are targeting the `master` branch.
+2. Read contributing guidelines:
+   https://github.com/go-gitea/gitea/blob/master/CONTRIBUTING.md
+3. Describe what your pull request does and which issue
+   you're targeting (if any)
 
-**You MUST delete above content including this line before posting; too lazy to take this action considered invalid pull request.**
+**You MUST delete above content including this line before posting;
+too lazy to take this action considered invalid pull request.**