Update Caddy reverse-proxy instructions (#11655)

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

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

 
 ```
 git.example.com {
-    proxy / http://localhost:3000
+    reverse_proxy localhost:3000
+}
+```
+
+If you still use Caddy v1, use:
+
+```
+git.example.com {
+    proxy / localhost:3000
 }
 ```
 
 
 ```
 git.example.com {
-    proxy /git/ http://localhost:3000 # Note: Trailing Slash after /git/
+    route /git/* {
+        uri strip_prefix /git
+        reverse_proxy localhost:3000
+    }
+}
+```
+
+Or, for Caddy v1:
+
+```
+git.example.com {
+    proxy /git/ localhost:3000
 }
 ```