Q: How can i add a description/caption to a image in the gallery?
A: From V1.6.0 , there is a better alternative to the description file - enter your description in the Joomla backend!
From V1.6.0, the is no need to create a description file for your image descriptions, simply enter the captions for your images in the backend!
In the module's configuration, switch to the tab 'advanced', and enter your caption in the following format:
imagename|caption or description
Do this for all images in your gallery for which you want to add a caption, always one image|caption combination on one line.
Save the module and take a look at the frontend output.