chore: remove closed issue documentation files

Removed 8 closed issue documentation files from docs/issues/:
- #216: epic-release-and-run-commands
- #217: demo-slice-release-run-commands
- #220: tracker-slice-release-run-commands
- #232: mysql-slice-release-run-commands
- #236: dynamic-tracker-ports-in-docker-compose
- #238: prometheus-slice-release-run-commands
- #246: grafana-slice-release-run-commands (2 files)

All these issues have been closed on GitHub and no longer need
local documentation files.

Remaining open issue: #241

Author: josecelano