Add an issue template for reporting bugs

Try and collect as much information as possible from the reporter, for helping with debugging.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,38 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Desktop (please complete the following information):**
+- OS: [eg: MacOS Catalina]
+- Emacs Version: [This should be the output of `M-x emacs-version`]
+- Poppler Version: [eg: output of `brew info poppler` and similarly for other OSs]
+
+**pdf-tools (please complete the following information):**
+- `pdf-tools` Version: [`M-x package-list-packages` -> Search for `pdf-tools` -> Hit Enter and copy all the details that pop up in the Help buffer]
+- `pdf-tools` customization / configuration that you use
+
+**Additional context**
+- If you are reporting a crash, please try and add the Backtrace / Stacktrace of the crash. 
+- If you are reporting a bug, please try and attach an example PDF file where I can reproduce the bug.
+- Please try reproducing the bug yourself on Vanilla Emacs before reporting the problem.