feat(cops): Add support for running unsafe cops with latest RuboCop

Latest version of RuboCop now only performs auto-corrections from "safe"
cops when given the `--auto-correct`/`-a` option. To run
auto-corrections from all cops, including "unsafe" ones, you must now
pass in `--auto-correct-all`/`-A` instead.

The new `rubocopfmt-include-unsafe-cops` defcustom defaults to no `nil`,
for backwards compatibility. Turn on unsafe cops by setting it to `t`.

README.md

@@ -45,6 +45,19 @@ Place `rubocopfmt.el` somewhere into you `load-path` and require it. For example
 With `rubocopfmt-mode` enabled, Ruby buffer will automatically be formatted with
 RuboCop on save.
 
+### Unsafe Cops
+
+RuboCop no longer runs auto-corrections for unsafe cops. To enable unsafe cops,
+set `rubocopfmt-include-unsafe-cops` to `t`. If you're using use-package:
+
+```elisp
+(use-package rubocopfmt
+  :hook
+  (ruby-mode . rubocopfmt-mode)
+  :custom
+  (rubocopfmt-include-unsafe-cops t))
+```
+
 ## Commands
 
 - `rubocopfmt` - Format current buffer with RuboCop.