Update htpasswd command line in the docs

Closes cesanta#203

Author: rojer

examples/reference.yml

@@ -57,7 +57,7 @@ token:  # Settings for the tokens.
 
 # Static user map.
 users:
-  # Password is specified as a BCrypt hash. Use htpasswd -B to generate.
+  # Password is specified as a BCrypt hash. Use `htpasswd -nB USERNAME` to generate.
   "admin":
     password: "$2y$05$LO.vzwpWC5LZGqThvEfznu8qhb5SGqvBSWY1J3yZ4AxtMRZ3kN5jC"  # badmin
   "test":

examples/simple.yml

@@ -17,7 +17,7 @@ token:
   expiration: 900
 
 users:
-  # Password is specified as a BCrypt hash. Use htpasswd -B to generate.
+  # Password is specified as a BCrypt hash. Use `htpasswd -nB USERNAME` to generate.
   "admin":
     password: "$2y$05$LO.vzwpWC5LZGqThvEfznu8qhb5SGqvBSWY1J3yZ4AxtMRZ3kN5jC"  # badmin
   "test":