Create bug.md

Author: tjhunter

.github/ISSUE_TEMPLATE/bug.md

@@ -0,0 +1,36 @@
+---
+name: Bug
+about: Create a report to help us improve.
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+ **❗ IMPORTANT:** If you have difficulties creating a dataset from any source,
+ please provide us with a sample data file or a URL to the source data.
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+** Version number **
+I am using the following versions/branch/sha1 of the anemoi packages
+(alternatively the output of `pip freeze`)
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Run this '....'
+3. See error
+
+**URL to sample input data**
+Provide a URL to a sample input data, or attach a file to that report if it is small enough.
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Additional context**
+Add any other context about the problem here.