Add mention of sudo's "secure_path" option in borgmatic installation documentation (#513).

NEWS

@@ -6,6 +6,7 @@
    once for each configured repository instead of once per configuration file. Additionally, the
    "repositories" interpolated variable has been changed to "repository", containing the path to the
    current repository for the hook.
+ * #513: Add mention of sudo's "secure_path" option in borgmatic installation documentation.
  * #515: Fix "borgmatic borg key ..." to pass parameters to Borg in correct order.
  * #516: Fix handling of TERM signal to exit borgmatic, not just forward the signal to Borg.
  * #517: Fix borgmatic exit code (so it's zero) when initial Borg calls fail but later retries

docs/how-to/set-up-backups.md

@@ -51,6 +51,11 @@ sudo borgmatic --version
 
 If borgmatic is properly installed, that should output your borgmatic version.
 
+As an alternative to adding the path to `~/.bashrc` file, if you're using sudo
+to run borgmatic, you can configure [sudo's
+`secure_path` option](https://man.archlinux.org/man/sudoers.5) to include
+borgmatic's path.
+
 
 ### Global install option