Rephrase documentation and link to docs on exit codes feature (#798).

NEWS

@@ -1,7 +1,9 @@
 1.8.7
  * #736: Store included configuration files within each backup archive in support of the "config
    bootstrap" action. Previously, only top-level configuration files were stored.
- * #798: Elevate specific Borg warnings to errors or squash errors to warnings.
+ * #798: Elevate specific Borg warnings to errors or squash errors to
+ * warnings. See the documentation for more information:
+   https://torsion.org/borgmatic/docs/how-to/customize-warnings-and-errors/
  * #810: SECURITY: Prevent shell injection attacks within the PostgreSQL hook, the MongoDB hook, the
    SQLite hook, the "borgmatic borg" action, and command hook variable/constant interpolation.
  * #814: Fix a traceback when providing an invalid "--override" value for a list option.

docs/how-to/customize-warnings-and-errors.md

@@ -82,5 +82,5 @@ a backup file is not found:
 terminating with warning status, rc 107
 ```
 
-The exit status to use in that case would be `107` if you want to configure
-borgmatic to treat it as an error.
+So if you want to configure borgmatic to treat this as an error instead of a
+warning, the exit status to use is `107`.