init docs

docs/ports.md

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+# Used ports
+
+This file explains which ports are used and for what reason (please categorize them somehow and sort if possible)
+
+## Shared usage
+22 - ssh
+80 - caddy
+443 - caddy
+1024 - gitea exposed on that port inside the server (not allowed to use from outside)
+1025 - gitea exposed it's ssh on that port (therefore allowed from outside)
+
+## Rules
+If you want to add some extra port, then please:
+1. Check prs of other people
+2. Use 1024+ (because user for caddy isn't root and I don't want to change smth so please)
+
+There will be more, but that's all for now