Remove everything specific to a Gitea deployment (closes #209)

Delete the Gitea compose setup, its document, its two scripts and their
make targets. Drop the Core Rule Set exclusions written for Gitea: the
ten query parameters skipped by rules 930120, 932160 and 932260, and the
gitea_flash and redirect_to cookies. The remaining changes are
renumbered, five in all. Documents and tests use neutral examples.

Model: opus-5-5

docs/rules.md

@@ -55,10 +55,10 @@ empty-agent      user_agent  log     ^$
 ## A file of your own
 
 `servewaf` reads the rule files in its own container. Rules of your own go in a
-file named to sort after the default, such as `50-gitea.rules`:
+file named to sort after the default, such as `50-site.rules`:
 
 ```
-# 50-gitea.rules: WordPress probes, which gitea never serves
+# 50-site.rules: WordPress probes, which this site never serves
 wp-probe         path        ban     (?i)^/(wp-login\.php|xmlrpc\.php|wp-admin/)
 ```
 
@@ -66,7 +66,7 @@ A `Dockerfile` built on the `smallwebwaf` image, for `servewaf` to run from,
 adds it:
 
 ```dockerfile
-COPY 50-gitea.rules /etc/smallwebwaf/rules.d/50-gitea.rules
+COPY 50-site.rules /etc/smallwebwaf/rules.d/50-site.rules
 ```
 
 Or mount it there. A `path` rule applies on every site behind that `servewaf`.