Remove markdown link check

This CI job is incredibly flaky and provides little value.
Remove it to reduce maintenance burden.

Author: lopopolo

.github/markdown-link-check.json

@@ -159,8 +159,10 @@ rake lint:eslint                   # Lint JavaScript and TypeScript sources with
 rake lint:rubocop                  # Run RuboCop
 rake lint:rubocop:autocorrect      # Autocorrect RuboCop offenses (only when it's safe)
 rake lint:rubocop:autocorrect_all  # Autocorrect RuboCop offenses (safe and unsafe)
-rake release:markdown_link_check   # Check for broken links in markdown files
 rake test                          # Run Playground unit tests
+rake toolchain:sync                # Sync Rust toolchain to all sources
+rake toolchain:sync:ci             # Sync the root rust-toolchain version to CI jobs
+rake toolchain:sync:manifests      # Sync the root rust-toolchain version to all crate manifests
 ```
 
 To lint Ruby sources, the playground uses [RuboCop]. RuboCop runs as part of the

.github/workflows/markdown-link-check.yaml

@@ -101,26 +101,6 @@ end
 
 Bundler::Audit::Task.new
 
-namespace :release do
-  link_check_files = FileList.new('**/*.md') do |f|
-    f.exclude('emsdk/**/*')
-    f.exclude('node_modules/**/*')
-    f.exclude('**/target/**/*')
-    f.exclude('**/vendor/*/**/*')
-    f.include('*.md')
-    f.include('**/vendor/*.md')
-  end
-
-  link_check_files.sort.uniq.each do |markdown|
-    desc 'Check for broken links in markdown files'
-    task markdown_link_check: markdown do
-      command = ['npx', 'markdown-link-check', '--config', '.github/markdown-link-check.json', markdown]
-      sh command.shelljoin
-      sleep(rand(1..5))
-    end
-  end
-end
-
 namespace :toolchain do
   desc 'Sync Rust toolchain to all sources'
   task sync: %i[sync:manifests sync:ci]