Add redirect for port forwarding guide (PaperMC#92)

Author: PJB3005

book.toml

@@ -72,6 +72,7 @@ warning-policy = "ignore" # false-positives like hell with absolute links & late
 "/en/hosting/SS14-Admin/index.html" = "/en/server-hosting/setting-up-ss14-admin.html"
 "/en/hosting/robust-cdn/index.html" = "/en/server-hosting/setting-up-robust-cdn.html"
 "/en/hosting/oauth/index.html" = "/en/server-hosting/oauth.html"
+"/en/hosting/port-forwarding/index.html" = "/en/server-hosting/port-forwarding.html"
 "/en/technical-docs/acronyms-and-nomenclature/index.html" = "/en/general-development/codebase-info/acronyms-and-nomenclature.html"
 "/en/getting-started/engine-changes/index.html" = "/en/general-developmnet/codebase-info/prs-with-engine-changes.html"
 "/en/getting-started/debugging-tools/index.html" = "/en/general-development/tips/debugging-tools.html"