Ignore /public/docs

A generated API documentation was added, so instead of viewing an out of
date documentation on the Web it's possible to manually generate the
API documentation.
The documentation is generated under public/docs, so to prevent the
committing of a documentation this directory is added to the ignore
list.

.gitignore

@@ -1,6 +1,7 @@
 /node_modules
 /public/hot
 /public/storage
+/public/docs
 /storage/*.key
 /vendor
 /.idea