Added

• strings2: Added a reference to the book chapter for reference conversion
• lifetimes: Added a link to the lifetimekata project
• Added a new tests4 exercises, which teaches about testing for panics
• Added a ! prefix command to watch mode that runs an external command
• Added a --success-hints option to watch mode that shows hints on exercise success

Changed

• vecs2: Renamed iterator variable bindings for clarify
• lifetimes: Changed order of book references
• hashmaps2: Clarified instructions in the todo block
• Moved lifetime exercises before test exercises (via the recommended book ordering)
• options2: Improved tests for layering options
• modules2: Added more information to the hint

Fixed

• errors2: Corrected a comment wording
• iterators2: Fixed a spelling mistake in the hint text
• variables: Wrapped the mut keyword with backticks for readability
• move_semantics2: Removed references to line numbers
• cow1: Clarified the owned_no_mutation comments
• options3: Changed exercise to panic when no match is found
• rustlings lsp now generates absolute paths, which should fix VSCode rust-analyzer usage on Windows

Housekeeping

• Added a markdown linter to run on GitHub actions
• Split quick installation section into two code blocks