update option description

Author: lahmatiy

README.md

@@ -31,16 +31,18 @@ Options:
 
       --comments <value>    Comments to keep: exclamation (default), first-exclamation or none
       --debug [level]       Output intermediate state of CSS during compression
-      --declaration-list    Treats input as declaration list
+  -d, --declaration-list    Treat input as a declaration list
+      --force-media-merge   Enables unsafe merge of @media rules
   -h, --help                Output usage information
   -i, --input <filename>    Input file
       --input-map <source>  Input source map: none, auto (default) or <filename>
   -m, --map <destination>   Generate source map: none (default), inline, file or <filename>
   -o, --output <filename>   Output file (result outputs to stdout if not set)
       --restructure-off     Turns structure minimization off
       --stat                Output statistics in stderr
-  -u, --usage <filenane>    Usage data file
+  -u, --usage <filename>    Usage data file
   -v, --version             Output version
+      --watch               Watch source file for changes
 ```
 
 Some examples: