There are 8 shp tags and it has no wiki. I think making the extension of shapefiles an alias makes sense.
A hint. One way to see if a tag has synonyms is:
Click on the tag shp, for example. You will see this:
The red circle shows there is one (1) synonym of shp. Click on "synonyms" to see all tags and which one is the master.
In the above screenshot we can see shp was made a synonym of shapefile (the master tag).