docs(admin): add wordpress docs (#552)

Closes #551

Signed-off-by: Xe Iaso <me@xeiaso.net>

docs/docs/admin/frameworks/wordpress.mdx

@@ -0,0 +1,39 @@
+# Wordpress
+
+Wordpress is the most popular blog engine on the planet.
+
+## Using a multi-site setup with Anubis
+
+If you have a multi-site setup where traffic goes through Anubis like this:
+
+```mermaid
+---
+title: Apache as tls terminator and HTTP router
+---
+
+flowchart LR
+    T(User Traffic)
+    subgraph Apache 2
+        TCP(TCP 80/443)
+        US(TCP 3001)
+    end
+
+    An(Anubis)
+    B(Backend)
+
+    T --> |TLS termination| TCP
+    TCP --> |Traffic filtering| An
+    An --> |Happy traffic| US
+    US --> |whatever you're doing| B
+```
+
+Wordpress may not realize that the underlying connection is being done over HTTPS. This could lead to a redirect loop in the `/wp-admin/` routes. In order to fix this, add the following to your `wp-config.php` file:
+
+```php
+if (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https') {
+    $_SERVER['HTTPS'] = 'on';
+    $_SERVER['SERVER_PORT'] = 443;
+}
+```
+
+This will make Wordpress think that your connection is over HTTPS instead of plain HTTP.