docs: make sure rtspclientsink plugin docs index page is called index.html

.. instead of plugin-index.html.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2592>

subprojects/gst-rtsp-server/docs/meson.build

@@ -37,7 +37,7 @@ else
         required: false)
 endif
 
-plugins_cache = join_paths(meson.current_source_dir(), 'gst_plugins_cache.json')
+plugins_cache = join_paths(meson.current_source_dir(), 'plugins', 'gst_plugins_cache.json')
 if plugins.length() == 0
     message('All rtsp-server plugins have been disabled')
 elif plugins_cache_generator.found()
@@ -95,9 +95,9 @@ libs_doc = [hotdoc.generate_doc('gst-rtsp-server',
 
 plugins_doc = [hotdoc.generate_doc('rtspclientsink',
     project_version: api_version,
-    sitemap: 'plugin-sitemap.txt',
-    index: 'plugin-index.md',
-    gst_index: 'plugin-index.md',
+    sitemap: 'plugins/sitemap.txt',
+    index: 'plugins/index.md',
+    gst_index: 'plugins/index.md',
     gst_c_sources: ['../gst/rtsp-sink/*.[ch]'],
     gst_dl_sources: [rtspsink.full_path()],
     gst_smart_index: true,