Refactored documentation for Docker hub workflow

- Readme size lowered to 18KB
- Documents created in doc/ directory
- faq.md, firewall.md, development.md
- Title svg as absolute path for Docker hub
- Re-enabled Docker hub description workflow

doc/firewall.md

@@ -0,0 +1,39 @@
+# Firewall
+
+If you have a strict firewall setup (host level or router level), you might want to setup the following.
+
+## Start only
+
+The following is required when the container starts only:
+
+- Allow outbound TCP 443 to github.com
+- If `DOT=on`, allow outbound TCP 853 to allow Unbound to resolve github.com and the PIA subdomain name if you use PIA.
+- If `DOT=off` and `VPNSP=pia`, allow outbound UDP 53 to your DNS provider to resolve the PIA subdomain name.
+
+## VPN connections
+
+You need the following to allow communicating with the VPN servers
+
+### Private Internet Access
+
+- If `PIA_ENCRYPTION=strong` and `PROTOCOL=udp`: allow outbound UDP 1197 to the corresponding VPN server IPs
+- If `PIA_ENCRYPTION=normal` and `PROTOCOL=udp`: allow outbound UDP 1198 to the corresponding VPN server IPs
+- If `PIA_ENCRYPTION=strong` and `PROTOCOL=tcp`: allow outbound TCP 501 to the corresponding VPN server IPs
+- If `PIA_ENCRYPTION=normal` and `PROTOCOL=tcp`: allow outbound TCP 502 to the corresponding VPN server IPs
+
+### Mullvad
+
+- If `PORT=`, please refer to the mapping of Mullvad servers in [these source code lines](../internal/constants/mullvad.go#L64-L667) to find the corresponding UDP port number and IP address(es) of your choice
+- If `PORT=53`, allow outbound UDP 53 to the corresponding VPN server IPs, which you can fine in [the mapping of Mullvad servers](../internal/constants/mullvad.go#L64-L667)
+- If `PORT=80`, allow outbound TCP 80 to the corresponding VPN server IPs, which you can fine in [the mapping of Mullvad servers](../internal/constants/mullvad.go#L64-L667)
+- If `PORT=443`, allow outbound TCP 443 to the corresponding VPN server IPs, which you can fine in [the mapping of Mullvad servers](../internal/constants/mullvad.go#L64-L667)
+
+### Windscribe
+
+- If `PROTOCOL=udp`: allow outbound UDP 443 to the corresponding VPN server IPs
+- If `PROTOCOL=tcp`: allow outbound TCP 1194 to the corresponding VPN server IPs
+
+## Inbound connections
+
+- If `SHADOWSOCKS=on`, allow inbound TCP 8388 and UDP 8388 from your LAN
+- If `TINYPROXY=on`, allow inbound TCP 8888 from your LAN