DOCSP-28142 Adds missing word (#2732)

Author: kennethdyer

source/includes/steps-run-mongodb-on-osx.yaml

@@ -40,7 +40,7 @@ action:
     Ensure that the user account running :binary:`~bin.mongod` has read
     and write permissions for these two directories. If you are running
     :binary:`~bin.mongod` as your own user account, and you just created
-    the two directories above, they should already accessible to your
+    the two directories above, they should already be accessible to your
     user. Otherwise, you can use ``chown`` to set ownership,
     substituting the appropriate user:
   language: sh