chore(makefile): remove replacevars ref

Was keeping this clean step around to try and passively remove this file
from users that may not be keeping track of upstream changes. Now we
should be good to delete it.

Signed-off-by: Randolph Sapp <[email protected]>

Author: StaticRocket

Makefile

@@ -56,7 +56,6 @@ help:
 
 clean:
 	rm -rf "$(BUILDDIR)"
-	rm -f source/_replacevars.rst
 
 lint:
 	rstcheck -r "$(SOURCEDIR)"