Renames Invite people button to Invite.

lang/main.json

         "hidePassword": "Hide password",
         "inviteTo": "Invite people to __conferenceName__",
         "invitedYouTo": "__userName__ has invited you to the __inviteURL__ conference",
-        "invitePeople": "Invite people",
+        "invitePeople": "Invite",
         "locked": "This call is locked. New callers must have the link and enter the password to join.",
         "showPassword": "Show password",
         "unlocked": "This call is unlocked. Any new caller with the link may join the call."