Update issue templates

Add template for calibration help that isn't necessarily a bug

.github/ISSUE_TEMPLATE/calibration-help.md

@@ -0,0 +1,16 @@
+---
+name: Calibration help
+about: If you're trying to use Rascal to calibrate a spectrum and are runnning into
+  trouble, you can use this template.
+title: ''
+labels: Calibration help
+assignees: ''
+
+---
+
+Please fill out the following information so we can help you best:
+
+- What instrument/data/lamp are you using? The more details the better.
+- What version of rascal are you using? How did you install it?
+- What have you tried - please post your script/configuration?
+- What went wrong?