Modify Nginx compatibility-layer location block to forward not just client stuff to matrix-synapse

Before the change, it did just just forward `/_matrix` & `/_synapse/client` to synapse.

docs/setup/reverse-proxy.md

@@ -94,7 +94,7 @@ server {
 
     # Forward to Synapse
     # as per https://element-hq.github.io/synapse/latest/reverse_proxy.html#nginx
-    location ~ ^(/_matrix|/_synapse/client) {
+    location ~ ^(/_matrix|/_synapse) {
         proxy_pass http://localhost:8008;
         proxy_set_header X-Forwarded-For $remote_addr;
         proxy_set_header X-Forwarded-Proto $scheme;