Add new issue template, just for bugs.

.github/bug.md

@@ -0,0 +1,35 @@
+---
+labels: bug
+---
+
+# Bug Report
+## To assist in resolving your issue, fill out this form completely. Omitting information will delay the resolution of your issue.
+
+- [ ] Have you reviewed the NERDTree documentation? `:h NERDTree`
+- [ ] Have you looked for an answer to your question in the [Wiki](https://github.com/scrooloose/nerdtree/wiki)?
+
+### Environment
+<!--- Describe your Vim/NERDTree setup. -->
+
+- [ ] Operating System: 
+- [ ] Vim version `:version`: 
+- [ ] NERDTree version `git rev-parse --short HEAD`: 
+- [ ] NERDTree settings applied in your vimrc, if any:
+    ```vim
+    ```
+
+### Process
+<!--- List the steps that will recreate the issue. -->
+
+1. 
+
+### Current Result
+<!--- Describe what you you currently experience from this process. -->
+
+### Expected Result
+<!--- Describe what you would have expected from this process. -->
+
+### Screenshot(s)
+
+### Possible Fix
+<!--- If you have explored the code, share what you've found. -->