Keep only important node rules in GitBook.gitignore

GitBook.gitignore

-# Logs
-logs
-*.log
-
-# Runtime data
-pids
-*.pid
-*.seed
-
-# Directory for instrumented libs generated by jscoverage/JSCover
-lib-cov
-
-# Coverage directory used by tools like istanbul
-coverage
-
-# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+# Node rules:
+## Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
 .grunt
 
-# Compiled binary addons (http://nodejs.org/api/addons.html)
-build/Release
-
-# Dependency directory
-# Commenting this out is preferred by some people, see
-# https://npmjs.org/doc/faq.html#Should-I-check-my-node_modules-folder-into-git
+## Dependency directory
+## Commenting this out is preferred by some people, see
+## https://npmjs.org/doc/faq.html#Should-I-check-my-node_modules-folder-into-git
 node_modules
 
-# Users Environment Variables
-.lock-wscript
-
 # Book build output
 _book