Add AllowEncodedSlashes to apache (#5068)

* Add AllowEncodedSlashes to apache

Add `AllowEncodedSlashes On` to apache config to support encoding for v3 rooms. "The AllowEncodedSlashes setting is not inherited by virtual hosts, and virtual hosts are used in many default Apache configurations, such as the one in Ubuntu. The workaround is to add the AllowEncodedSlashes setting inside a <VirtualHost> container (/etc/apache2/sites-available/default in Ubuntu)." Source: https://stackoverflow.com/questions/4390436/need-to-allow-encoded-slashes-on-apache

* change allowencodedslashes to nodecode

docs/reverse_proxy.rst

@@ -69,6 +69,7 @@ Let's assume that we expect clients to connect to our server at
           SSLEngine on
           ServerName matrix.example.com;
 
+          AllowEncodedSlashes NoDecode
           ProxyPass /_matrix http://127.0.0.1:8008/_matrix nocanon
           ProxyPassReverse /_matrix http://127.0.0.1:8008/_matrix
       </VirtualHost>
@@ -77,6 +78,7 @@ Let's assume that we expect clients to connect to our server at
           SSLEngine on
           ServerName example.com;
           
+          AllowEncodedSlashes NoDecode
           ProxyPass /_matrix http://127.0.0.1:8008/_matrix nocanon
           ProxyPassReverse /_matrix http://127.0.0.1:8008/_matrix
       </VirtualHost>