Update README.md

Author: danielbachhuber

README.md

@@ -4986,6 +4986,10 @@ wp user meta get <user> <key> [--format=<format>]
     $ wp user meta get 123 bio
     Mary is an WordPress developer.
 
+    # Get the primary site of a user (for multisite)
+    $ wp user meta get 2 primary_blog
+    3
+
 
 
 ### wp user meta list