Add RuboCop RSpec support

Previously, RuboCop RSpec failed to detect RSpec aliases. A number of
cops were failing false offences, and some cops were unable to lint, as
they were skipping locally defined RSpec aliases taking them for
arbitrary blocks and method calls.

See:
 - rubocop/rubocop-rspec#1077
 - rubocop/rubocop-rspec#956

Sibling pull requests:
 - palkan/action_policy#138

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## master (unrealeased)
 
+- Add support for RSpec aliases detection when linting specs using `let_it_be`/`before_all` with `rubocop-rspec` 2.0 ([@pirj][])
+
 ## 0.12.2 (2020-09-03)
 
 - Execute Minitest `before_all` in the context of the current test object. ([@palkan][])

config/rubocop-rspec.yml

@@ -0,0 +1,6 @@
+RSpec:
+  Language:
+    Helpers:
+      - let_it_be
+    Hooks:
+      - before_all

docs/README.md

@@ -88,6 +88,16 @@ Supported Ruby versions:
 
 Supported RSpec version (for RSpec features only): >= 3.5.0 (for older RSpec version use TestProf < 0.8.0).
 
+### Linting with RuboCop RSpec
+
+When you lint your RSpec spec files with `rubocop-rspec`, it will fail to properly detect RSpec constructs that TestProf defines, `let_it_be` and `before_all`.
+Make sure to use `rubocop-rspec` 2.0 or newer and add the following to your `.rubocop.yml`:
+
+```yaml
+inherit_gem:
+  test-prof: config/rubocop-rspec.yml
+```
+
 ## Profilers
 
 - [RubyProf Integration](./profilers/ruby_prof.md)