[DO NOT MERGE] [Issue #486] Local storage is now stored per hostname (for subdomains)

[dmed256]

Please makes sure these boxes are checked before submitting your PR, thank you!

• Make sure you are merging your commits to master branch.
• Add some descriptions and refer relative issues for you PR.
• DO NOT include files inside lib directory.

---

• [docsify.search.index引发的问题及建议 #486] Search stores expiration and index information per hostname to support subdomains

[dmed256]

Oops, misread the issue...
I think instead of window.location.hostname it needs to use config.basePath

[yinheli]

It is not applicable with one domain with multi docsify instance.
Why not add search key prefix for config? #553