Add gitignore for Gatsby projects

gatsby.gitignore

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+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+junit.xml
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (http://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directory
+# https://www.npmjs.org/doc/misc/npm-faq.html#should-i-check-my-node_modules-folder-into-git
+node_modules
+jspm_packages/
+integration-tests/gatsby-cli/execution-folder/*
+*.un~
+dist
+bin/published.js
+
+# Typescript v1 declaration files
+typings/
+
+# Build Path of Test Fixtures
+test/**/public
+.gatsby-context.js
+.DS_Store
+public/
+node_modules/
+e2e-tests/gatsby-pnp/
+__diff_output__/
+.cache/
+.netlify
+.Rhistory
+
+# Optional npm cache directory
+.npm
+
+# IDE specific
+.idea/
+.vscode/
+*.sw*
+
+# misc
+.serverless/
+.eslintcache
+scripts/.env
+
+# lock files
+yarn.lock
+package-lock.json
+# ignore any lock file other than main lock file
+!/yarn.lock
+
+# starters are special; we want to persist the lock files
+!starters/*/package-lock.json
+
+.parcel-cache
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# dotenv environment variable files
+.env*
+
+# Mac files
+.DS_Store
+
+# Yarn
+yarn-error.log
+.pnp/
+.pnp.js
+# Yarn Integrity file
+.yarn-integrity