Apply suggestions from code review

Co-authored-by: Aleksandr Petrosyan <a-p-petrosyan@yandex.ru>
Signed-off-by: Ekaterina Mekhnetsova <mekkatya@gmail.com>

src/guide/advanced/isi.md

@@ -124,9 +124,9 @@ are assumed to be non-negative as well, so you can never have `-1.0` of
 
 These are used for [permissions and roles](permissions.md).
 
-`Grant` operation is used to permanently grant a user either a single
+`Grant` is used to permanently grant a user either a single
 permission, or a group of permissions (a "role"). Granted roles and
-permissions can only be removed via `Revoke` instruction. As such, these
+permissions can only be removed via the `Revoke` instruction. As such, these
 instructions should be used carefully.
 
 ### `SetKeyValue`/`RemoveKeyValue`