Add apt_upgrade rule (#761)

* apt_list_upgradable: Prepend sudo to suggestion if used in command

* Add apt_upgrade rule

This suggests `apt upgrade` after `apt list --upgradable` if there are
packages to upgrade. It pairs well with the `apt_list_upgradable` rule,
which suggests `apt list --upgradable` after `apt update` if there are
packages to upgrade.

* Add apt_upgrade rule to README

README.md

@@ -283,6 +283,7 @@ Enabled by default only on specific platforms:
 * `apt_get_search` – changes trying to search using `apt-get` with searching using `apt-cache`;
 * `apt_invalid_operation` – fixes invalid `apt` and `apt-get` calls, like `apt-get isntall vim`;
 * `apt_list_upgradable` – helps you run `apt list --upgradable` after `apt update`;
+* `apt_upgrade` – helps you run `apt upgrade` after `apt list --upgradable`;
 * `brew_cask_dependency` – installs cask dependencies;
 * `brew_install` – fixes formula name for `brew install`;
 * `brew_link` – adds `--overwrite --dry-run` if linking fails;