probably better apache config

the `ProxyPreserveHost` is necessary otherwise signature checks fail

the `X-Forwarded-Proto` fixes the mastodon emulation (without it, it
tries to talk to `http://sharkey.example` and can fail)

the `ProxyPassReverse` are now the same as in my own configuration,
still not sure how useful they are (they tell apache to rewrite
`location` headers in responses)

thanks to tauroid on Discord for noticing the problems and helping me
debug the configuration

content/en/docs/install/fresh.md

@@ -388,14 +388,21 @@ Something like this works for Apache 2.4.47 or later:
  ServerName sharkey.example
 
  SSLEngine On
+ RequestHeader set X-Forwarded-Proto "https"
 
  AllowEncodedSlashes NoDecode
 
+ ProxyPreserveHost On
+
  ProxyPass "/" "http://127.0.0.1:3000/" upgrade=websocket
+ ProxyPassReverse "/" "https://sharkey.example/"
+ ProxyPassReverse "/" "http://127.0.0.1:3000/"
+
  # or, if your Sharkey listens on a UNIX socket
  # ProxyPass "/" "unix:/opt/sharkey/sharkey.sock|http://127.0.0.1/" upgrade=websocket
+ # ProxyPassReverse "/" "https://sharkey.example/"
+ # ProxyPassReverse "/" "unix:/opt/sharkey/sharkey.sock|http://127.0.0.1/"
 
- ProxyPassReverse / https://sharkey.example/
 </VirtualHost>
 ```