github: add an issue template for bugs only on main instance

.github/ISSUE_TEMPLATE/bug-main-instance.md

@@ -0,0 +1,36 @@
+---
+name: main instance bug report
+about: report an issue with cobalt.tools or api.cobalt.tools
+title: '[short description of the bug]'
+labels: main instance issue
+assignees: ''
+
+---
+
+### bug description
+clear and concise description of what the issue is.
+
+### reproduction steps
+steps to reproduce the described behavior.  
+here's an example of what it could look like:
+1. go to '...'
+2. click on '....'
+3. download [media type] from [service]
+4. see error
+
+### screenshots
+if applicable, add screenshots or screen recordings to support your explanation.  
+if not, remove this section.
+
+### links
+if applicable, add links that cause the issue. more = better.  
+if not, remove this section.
+
+### platform information
+- OS [e.g. iOS, windows]
+- browser [e.g. chrome, safari, firefox]
+- version [e.g. 115]
+
+### additional context
+add any other context about the problem here if applicable.  
+if not, remove this section.