chore: no free form issues, 'description'-s to 'placeholders'-s (#16)

## Description

There were some problems with the roll-out of the issue templates. This PR addresses them.

## Changes

- Disable `blank-issue-enabled`.
- Move all `description` types in the issue templates to `placeholder`.

### Design Decisions

- The `description` fields take up too much space.

## Checklist

- [x] Tests pass
- [x] Docs updated

Reviewed-on: #16
Co-authored-by: M.V. Hutz <git@maximhutz.me>
Co-committed-by: M.V. Hutz <git@maximhutz.me>

.gitea/ISSUE_TEMPLATE/BUG_REPORT.yml

@@ -7,20 +7,20 @@ body:
     id: context
     attributes:
       label: Context
-      description: What circumstances led to the bug?
+      placeholder: What circumstances led to the bug?
     validations:
       required: true
   - type: textarea
     id: expected-behavior
     attributes:
       label: Expected Behavior
-      description: What did you expect would happen?
+      placeholder: What did you expect would happen?
     validations:
       required: true
   - type: textarea
     id: actual-behavior
     attributes:
       label: Actual Behavior
-      description: What happened, and why was it unexpected?
+      placeholder: What happened, and why was it unexpected?
     validations:
       required: true