Fix command docs, automate API doc generation (#327)

Co-authored-by: Dennis Ploeger <develop@dieploegers.de>
Co-authored-by: dploeger <dploeger@users.noreply.github.com>

docs/api/ESCObject.md

@@ -78,4 +78,15 @@ Set the state and start a possible animation
 #### Parameters
 
 - p_state: State to set
-- immediate: If true, skip directly to the end
+- immediate: If true, skip directly to the end
+
+### get\_save\_data
+
+```gdscript
+func get_save_data() -> Dictionary
+```
+
+Return the data of the object to be inserted in a savegame file.
+
+**Returns**
+A dictionary containing the data to be saved for this object.