Since 0.5.[678] had broken deps & 0.5.9 requires nim>2, put in a note

about how to use older nim, if one must (although you probably need
a much smarter package management strategy than nimble to do so) as
per #9 (comment)

adix.nimble

@@ -9,6 +9,7 @@ requires "nim >= 2.0.0"
 requires "cligen >= 1.6.15"
 skipDirs = @[ "tests" ]
 
+# Older Nim must use adix < 0.5.5 & comment out the below `bin`.
 bin = @[
  "util/lfreq", # Somewhat efficient line frequency calculator
 ]