Updated README w/ usage for new partitions command

Author: jwolski

README.md

@@ -9,17 +9,18 @@ Command-line tools for Ringpop
 
   Commands:
 
-    checksums   Prints membership checksums
-    dist        Distribution of keyspace
-    dump        Dump membership information to disk
-    count       Counts members
-    leave       Makes node leave the cluster
-    list        List member information
-    lookup      Lookup a key in the ring
-    join        Makes node (re)join the cluster
-    status      Status of members in ring
-    top         General membership information
-    help [cmd]  display help for [cmd]
+    checksums    Prints membership checksums
+    dist         Distribution of keyspace
+    dump         Dump membership information to disk
+    count        Counts members
+    leave        Makes node leave the cluster
+    list         List member information
+    lookup       Lookup a key in the ring
+    join         Makes node (re)join the cluster
+    status       Status of members in ring
+    partitions   Show partition information of a ring
+    top          General membership information
+    help [cmd]   display help for [cmd]
 
   Command-line tools for Ringpop