fixup! Add factoring part to normscache

Author: ncw

README.md

@@ -6,9 +6,11 @@ Some docs here one day
 
 Build the norms cache
 
+Need the factor binary from github.com/michel-leonard/C-Quadratic-Sieve
+
 ```
-  # Create factors.sorted.txt .
-  ./cmd/normscache/normscache build factors.sorted.txt norms
+  ./cmd/normscache/normscache factor /path/to/factor factors.txt
+  ./cmd/normscache/normscache build factors.txt norms
   ./cmd/normscache/normscache tree norms
   ./cmd/normscache/normscache query norms 5 13 17 29 61
 ```