Add an issue template

With improvements by Clive Chan and Adric Norris.

Signed-off-by: Clive Chan <cc@clive.io>
Signed-off-by: Adric Norris <landstander668@gmail.com>
Signed-off-by: Brendan Forster <brendan@github.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,62 @@
+ - [ ] I was not able to find an [open](https://github.com/git-for-windows/git/issues?q=is%3Aopen)
+   or [closed](https://github.com/git-for-windows/git/issues?q=is%3Aclosed) issue
+   matching what I'm seeing
+
+### Setup
+
+ - Which version of Git for Windows are you using? Is it 32-bit or 64-bit?
+
+```
+$ git --version --build-options
+_TODO_
+```
+
+ - Which version of Windows are you running? Vista, 7, 8, 10? Is it 32-bit or 64-bit?
+
+```
+$ cmd.exe /c ver
+_TODO_
+```
+
+ - What options did you set as part of the installation? Or did you choose the
+   defaults?
+
+```
+# One of the following:
+> type "C:\Program Files\Git\etc\install-options.txt"
+> type "C:\Program Files (x86)\Git\etc\install-options.txt"
+> type "%USERPROFILE%\AppData\Local\Programs\Git\etc\install-options.txt"
+$ cat /etc/install-options.txt
+_TODO_
+```
+
+ - Any other interesting things about your environment that might be related
+   to the issue you're seeing?
+
+ _TODO_
+
+### Details
+
+ - Which terminal/shell are you running Git from? e.g Bash/CMD/PowerShell/other
+
+ _TODO_
+
+ - What commands did you run to trigger this issue? If you can provide a
+   [Minimal, Complete, and Verifiable example](http://stackoverflow.com/help/mcve)
+   this will help us understand the issue.
+
+```
+TODO
+```
+ - What did you expect to occur after running these commands?
+
+ _TODO_
+
+ - What actually happened instead?
+
+ _TODO_
+
+ - If the problem was occurring with a specific repository, can you provide the
+   URL to that repository to help us with testing?
+
+ _TODO_