Update cas docs

website/source/docs/commands/kv/delete.html.markdown.erb

@@ -21,9 +21,8 @@ Usage: `consul kv delete [options] KEY_OR_PREFIX`
 
 #### KV Delete Options
 
-* `-cas` - Perform a Check-And-Set operation. If this value is specified without
-  -modify-index, the key will first be fetched and the resulting ModifyIndex
-  will be used on the next query. The default value is false.
+* `-cas` - Perform a Check-And-Set operation. Specifying this value also
+  requires the -modify-index flag to be set. The default value is false.
 
 * `-modify-index=<int>` - Unsigned integer representing the ModifyIndex of the
   key. This is used in combination with the -cas flag.

website/source/docs/commands/kv/put.html.markdown.erb

@@ -24,9 +24,8 @@ Usage: `consul kv put [options] KEY [DATA]`
   operation will create the key and obtain the lock. The session must already
   exist and be specified via the -session flag. The default value is false.
 
-* `-cas` - Perform a Check-And-Set operation. If this value is specified without
-  -modify-index, the key will first be fetched and the resulting ModifyIndex
-  will be used on the next query. The default value is false.
+* `-cas` - Perform a Check-And-Set operation. Specifying this value also
+  requires the -modify-index flag to be set. The default value is false.
 
 * `-flags=<int>` - Unsigned integer value to assign to this key-value pair. This
   value is not read by Consul, so clients can use this value however makes sense