README.md in rbs-2.0.0 vs README.md in rbs-2.1.0

@@ -50,10 +50,15 @@
   end
 end
 ```
 <!-- run-end -->
 
+## The Target Version
+
+* The standard library signatures targets Ruby 3.1. (The latest release of Ruby.)
+* The library code targets Ruby 3.1, 3.0, and 2.7. (It runs on 2.6 in fact.)
+
 ## Installation
 
 Install the `rbs` gem. `$ gem install rbs` from the command line, or add a line in your `Gemfile`.
 
 ```rb
@@ -120,10 +125,10 @@
 ```
 <!-- run-end -->
 
 ## Guides
 
-- [Standard library signature contribution guide](docs/CONTRIBUTING.md)
+- [Core and standard library signature contribution guide](docs/CONTRIBUTING.md)
 - [Writing signatures guide](docs/sigs.md)
 - [Stdlib signatures guide](docs/stdlib.md)
 - [Syntax](docs/syntax.md)
 
 ## Development