Prefixless subtitle sidecar files

docs/usage.rst

@@ -33,11 +33,33 @@ Useful overrides include:
 * ``--no-pattern`` to skip database pattern matching
 * ``--show``, ``--season``, and ``--episode`` for explicit episode identity
 * ``--output-directory`` for generated output placement
-* ``--subtitle-directory`` and ``--subtitle-prefix`` for sidecar subtitle
-  imports
+* ``--subtitle-directory`` for source-basename sidecar subtitle imports
+* ``--subtitle-prefix`` for explicit or configured-prefix subtitle imports
+* ``--subtitle-extension`` to select the imported sidecar format (default:
+  ``vtt``)
+* ``--yes`` to accept a valid partial sidecar set without prompting
 * ``--copy-video`` or ``--copy-audio`` to preserve selected stream types
 * ``--rename-only`` for filename normalization without media rewriting
 
+Directory-only subtitle import matches the source basename. For example,
+``A2_t01.mkv`` discovers files such as ``A2_t01_2_deu_DEF.vtt`` in the
+provided directory:
+
+.. code-block:: sh
+
+   ffx convert --subtitle-directory /path/to/subtitles A2_t01.mkv
+
+Select a different sidecar set by extension, with or without the leading dot:
+
+.. code-block:: sh
+
+   ffx convert --subtitle-directory /path/to/subtitles \
+     --subtitle-extension .mkv A2_t01.mkv
+
+When only some source subtitle tracks have matching sidecar files, conversion
+asks for confirmation. Use ``--yes`` to substitute that valid subset without
+prompting. ``--yes`` also permits this case when ``--no-prompt`` is set.
+
 Manage Shows And Patterns
 -------------------------