Add server mode status to -V option

.github/ISSUE_TEMPLATE/bug_report.md

@@ -38,7 +38,7 @@ output by `rubocop -V`, include them as well. Here's an example:
 
 ```
 $ [bundle exec] rubocop -V
-1.35.1 (using Parser 2.7.2.0, rubocop-ast 1.1.1, running on ruby 2.7.2 x86_64-linux)
+1.35.1 (using Parser 2.7.2.0, rubocop-ast 1.1.1, running on ruby 2.7.2) [x86_64-linux]
   - rubocop-performance 1.9.1
   - rubocop-rspec 2.0.0
 ```

CONTRIBUTING.md

@@ -17,7 +17,7 @@ do so.
 
 ```console
 $ rubocop -V
-1.35.1 (using Parser 2.7.2.0, rubocop-ast 1.1.1, running on ruby 2.7.2 x86_64-linux)
+1.35.1 (using Parser 2.7.2.0, rubocop-ast 1.1.1, running on ruby 2.7.2) [x86_64-linux]
   - rubocop-performance 1.9.1
   - rubocop-rspec 2.0.0
 ```

changelog/change_add_server_mode_to_version_option.md

@@ -0,0 +1 @@
+* [#10940](https://github.com/rubocop/rubocop/pull/10940): Add server mode status to `-V` option. ([@koic][])

lib/rubocop/version.rb

@@ -7,7 +7,7 @@ module Version
 
     MSG = '%<version>s (using Parser %<parser_version>s, ' \
           'rubocop-ast %<rubocop_ast_version>s, ' \
-          'running on %<ruby_engine>s %<ruby_version>s %<ruby_platform>s)'
+          'running on %<ruby_engine>s %<ruby_version>s)%<server>s [%<ruby_platform>s]'
 
     CANONICAL_FEATURE_NAMES = { 'Rspec' => 'RSpec', 'Graphql' => 'GraphQL', 'Md' => 'Markdown',
                                 'Thread_safety' => 'ThreadSafety' }.freeze
@@ -19,6 +19,7 @@ def self.version(debug: false, env: nil)
         verbose_version = format(MSG, version: STRING, parser_version: Parser::VERSION,
                                       rubocop_ast_version: RuboCop::AST::Version::STRING,
                                       ruby_engine: RUBY_ENGINE, ruby_version: RUBY_VERSION,
+                                      server: Server.running? ? ' +server' : '',
                                       ruby_platform: RUBY_PLATFORM)
         return verbose_version unless env