Switch to single issue template in github

Author: jedahan

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,17 @@
+<!-- This template helps us help you faster, here are a few examples -->
+
+Describe the bug here
+
+<!-- share your system, shell, and terminal -->
+* System: Ubuntu 20.04 / macOS 10.15.0 / WSL on Windows 10
+* Terminal: st 0.8.2 / ghostty 1.0.1 / iTerm2 3.3.7
+* Shell: zsh v5.9
+
+<!-- starting with the following zshrc, can you reproduce the issue? -->
+
+```zsh
+# ~/.zshrc
+test -d ~/.geometry || git clone https://github.com/geometry-zsh/geometry.git ~/.geometry
+source ~/.geometry/geometry.zsh
+```
+<!-- please share whatever modifications are needed for us to reproduce the issue -->