update doc for StarDict action

Author: blahgeek

doc/actions.md

@@ -12,6 +12,7 @@ Some actions requires additional command to run that does not come with Minions.
 - **Push Notification**: Send push notification (to your phone). Requires *[ntfy](https://github.com/dschep/ntfy) (properly configured)*
 - **Clipboard History**: View clipboard history.
 - **Youdao Translate**: Translate.
+- **Lookup in StarDict**: Lookup words in [StarDict](http://stardict-4.sourceforge.net/). Requires [sdcv](https://dushistov.github.io/sdcv/) installed and dictionaries configured.
 - **Save as TXT**: Save text as .txt file in temp dir.
 
 And: