Add deprecation message

README.md

@@ -1,43 +1,3 @@
 # RSpec
 
-Behaviour Driven Development for Ruby
-
-# Description
-
-rspec is a meta-gem, which depends on the
-[rspec-core](https://github.com/rspec/rspec-core),
-[rspec-expectations](https://github.com/rspec/rspec-expectations)
-and [rspec-mocks](https://github.com/rspec/rspec-mocks) gems. Each of these
-can be installed separately and loaded in isolation using `require`. Among
-other benefits, this allows you to use rspec-expectations, for example, in
-Test::Unit::TestCase if you happen to prefer that style.
-
-Conversely, if you like RSpec's approach to declaring example groups and
-examples (`describe` and `it`) but prefer Test::Unit assertions and
-[mocha](https://github.com/freerange/mocha), [rr](https://github.com/rr/rr)
-or [flexmock](https://github.com/jimweirich/flexmock) for mocking, you'll be
-able to do that without having to install or load the components of RSpec that
-you're not using.
-
-## Documentation
-
-See http://rspec.info/documentation/ for links to documentation for all gems.
-
-## Install
-
-    gem install rspec
-
-## Setup
-
-    rspec --init
-
-## Contribute
-
-* [http://github.com/rspec/rspec-dev](http://github.com/rspec/rspec-dev)
-
-## Also see
-
-* [https://github.com/rspec/rspec-core](https://github.com/rspec/rspec-core)
-* [https://github.com/rspec/rspec-expectations](https://github.com/rspec/rspec-expectations)
-* [https://github.com/rspec/rspec-mocks](https://github.com/rspec/rspec-mocks)
-* [https://github.com/rspec/rspec-rails](https://github.com/rspec/rspec-rails)
+This branch is deprecated, please use main`.

lib/rspec.rb

@@ -1,3 +1,4 @@
+warn "This branch is deprecated. Please use `main`."
+
 require 'rspec/core'
 require 'rspec/version'
-