[release-notes] Fix typo

[Michael Catanzaro <mcatanzaro src gnome org>]

commit f19109cec212dc5921887331edc6fcfa2bf45359
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sat Sep 5 13:08:03 2020 -0500

    Fix typo

 help/C/index.page | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/help/C/index.page b/help/C/index.page
index 45b5678e..b4c03643 100644
--- a/help/C/index.page
+++ b/help/C/index.page
@@ -62,7 +62,7 @@
     user accounts through the new <gui>Parental Controls</gui> option in the
     <gui>Users</gui> section. Installed applications can be filtered from the
     application overview, preventing them from being launched by the managed
-    user. <gui>Parental Controls</gui> also integrates with exist
+    user. <gui>Parental Controls</gui> also integrates with existing
     <app>Software</app> application restrictions, allowing you to select which
     applications can be installed.</p>
     <p>Other improvements to <app>Settings</app> include a new fingerprint