docs: use secure links in .gitignore

Author: alexandear

docs/.gitignore

@@ -20,7 +20,7 @@ coverage
 # nyc test coverage
 .nyc_output
 
-# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
 .grunt
 
 # Bower dependency directory (https://bower.io/)
@@ -29,7 +29,7 @@ bower_components
 # node-waf configuration
 .lock-wscript
 
-# Compiled binary addons (http://nodejs.org/api/addons.html)
+# Compiled binary addons (https://nodejs.org/api/addons.html)
 build/Release
 
 # Dependency directories