doc: fix broken references

These pages never existed, let's not try to reference them.

src/pipewire/filter.h

@@ -36,7 +36,7 @@ extern "C" {
  * The filter object provides a convenient way to implement
  * processing filters.
  *
- * See also \ref page_filters and \ref page_core_api
+ * See also \ref page_core_api
  */
 struct pw_filter;
 

src/pipewire/impl-client.c

@@ -374,7 +374,6 @@ static const struct pw_context_events context_events = {
 /** Make a new client object
  *
  * \param core a \ref pw_context object to register the client with
- * \param ucred a ucred structure or NULL when unknown
  * \param properties optional client properties, ownership is taken
  * \return a newly allocated client object
  *

src/pipewire/impl-client.h

@@ -63,13 +63,13 @@ struct pw_impl_client;
  *
  * The client object will have its credentials filled in by the protocol.
  * This information is used to check if a resource or action is available
- * for this client. See also \ref page_access
+ * for this client.
  *
  * \section sec_page_client_types Types
  *
  * The client and server maintain a mapping between the client and server
  * types. All type ids that are in messages exchanged between the client
- * and server will automatically be remapped. See also \ref page_types.
+ * and server will automatically be remapped.
  *
  * \section sec_page_client_resources Resources
  *