Adding filter function to variable docs

Author: xenodium

README.org

@@ -280,6 +280,7 @@ Streaming is enabled by default. =(setq chatgpt-shell-streaming nil)= to disable
 | chatgpt-shell-openrouter-key                                     | OpenRouter key as a string or a function that loads and returns it.          |
 | chatgpt-shell-babel-headers                                      | Additional headers to make babel blocks work.                                |
 | chatgpt-shell--pretty-smerge-mode-hook                           | Hook run after entering or leaving ‘chatgpt-shell--pretty-smerge-mode’.      |
+| chatgpt-shell-model-filter                                       | A function that is applied ‘chatgpt-shell-models’ to determine               |
 | chatgpt-shell-source-block-actions                               | Block actions for known languages.                                           |
 | chatgpt-shell-default-prompts                                    | List of default prompts to choose from.                                      |
 | chatgpt-shell-anthropic-key                                      | Anthropic API key as a string or a function that loads and returns it.       |