fix phrasing in description of --insecure

Co-authored-by: Dave Trudgian <[email protected]>
Signed-off-by: jason yang <[email protected]>

endpoint.rst

@@ -192,7 +192,7 @@ the ``--insecure`` flag:
    INFO:    Remote "test" added.
    INFO:    Global option detected. Will not automatically log into remote.
 
-This flag causes HTTP used instead of HTTPS *for service discovery only*. The
+This flag causes HTTP to be used instead of HTTPS *for service discovery only*. The
 protocol used to access individual library-, build- and keyservice-URLs is
 determined by the contents of the service discovery file.