Remove reference to caddy v1 in docs (#24962) (#24964)

Backport #24962 by @techknowlogick

caddy v1 is loong eol. v2 should be used.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

docs/content/doc/administration/reverse-proxies.en-us.md

@@ -187,14 +187,6 @@ git.example.com {
 }
 ```
 
-If you still use Caddy v1, use:
-
-```apacheconf
-git.example.com {
-    proxy / localhost:3000
-}
-```
-
 ## Caddy with a sub-path
 
 In case you already have a site, and you want Gitea to share the domain name, you can setup Caddy to serve Gitea under a sub-path by adding the following to your server block in your Caddyfile:
@@ -208,14 +200,6 @@ git.example.com {
 }
 ```
 
-Or, for Caddy v1:
-
-```apacheconf
-git.example.com {
-    proxy /git/ localhost:3000
-}
-```
-
 Then set `[server] ROOT_URL = http://git.example.com/git/` in your configuration.
 
 ## IIS