HACKING.md: remove unneeded [,] in the description

This commit removes an unnecessary [] in the description.

Author: mvo5

HACKING.md

@@ -7,7 +7,7 @@ pytest.
 
 ## Setup
 
-To work on bootc-image-builder one needs a working Go [compiler/environment?]. See
+To work on bootc-image-builder one needs a working Go environment. See
 [go.mod](bib/go.mod). 
 
 To run the testsuite install the test dependencies as outlined in the