Ignore node modules in bin/check

[cb341]

Locally, the node modules are in the same directory as the rest of the project files (.).
This causes mdlint to lint unwanted library files, making bin/check unusable.

Before:

➜  applications-setup-guide git:(feature/update-check) bc | head
./node_modules/@docsearch/react/README.md:30: MD033 Inline HTML
./node_modules/zwitch/readme.md:109: MD001 Header levels should only increment by one level at a time
./node_modules/zwitch/readme.md:143: MD001 Header levels should only increment by one level at a time
./node_modules/zwitch/readme.md:17: MD007 Unordered list indentation
./node_modules/zwitch/readme.md:12: MD030 Spaces after list markers
./node_modules/zwitch/readme.md:13: MD030 Spaces after list markers
./node_modules/zwitch/readme.md:14: MD030 Spaces after list markers
./node_modules/zwitch/readme.md:15: MD030 Spaces after list markers
./node_modules/zwitch/readme.md:16: MD030 Spaces after list markers
./node_modules/zwitch/readme.md:20: MD030 Spaces after list markers
bundler: failed to load command: mdl (/Users/dani/.local/share/mise/installs/ruby/3.1.2/bin/mdl)

After:

➜  applications-setup-guide git:(feature/update-check) bc