Releasing R2.0.0.

This is a major update to the library, with many changes, including:

1. Updated APIs and removal of legacy/deprecated APIs and code
2. New features from merged community pull-requests
3. Code refactoring for quality and standards compliance
4. Transition from `travis-ci` to `Github workflows`
5. Updated documentation
6. General code modernization (including support for Ruby 3.x)

Author: evolve75

lib/tree/version.rb

@@ -35,5 +35,5 @@
 
 module Tree
   # Rubytree Package Version
-  VERSION = '2.0.0.pre'
+  VERSION = '2.0.0'
 end

rubytree.gemspec

@@ -98,6 +98,9 @@ Gem::Specification.new do |s|
 
     - Support for `CamelCase` methods names has bee removed.
 
+    - The predicate methods no longer have `is_` or `has_` prefixes. However,
+      aliases with these prefixes exist to support existing client code.
+
     - Use of integers as node names does not require the optional
       `num_as_name` flag.