Little update to README.md file to include index do string.guid() and string.isoDate()
`description` is defined on `any`

Fixes small omission to make the heading for `description()` match the headers for the methods around it.
Indents validate options in README
Merge pull request #208 from paulillo/doc-update

Small documentation update
Merge pull request #218 from strathmeyer/patch-1

`description` is defined on `any`
Merge pull request #219 from strathmeyer/patch-2

Indents validate options in README
Immutable schema objects. Closes #221
Update README.md
Merge pull request #224 from spumko/immutable

Immutable schema objects. Closes #221
upstream merge
Refactor string.hostname()