[site] Use real space in bookmarklet URL, not %20
[site] Use real space in bookmarklet URL, not %20

This change replaces `%20` instances with spaces in the `javascript:`
bookmarklet URLs in the site `index.html`. (The `%20` instances in the
bookmarklet contents broke the Travis build, because we know check
(parse) those contents using Acorn, and they cause parse errors.)

takenspc/validator,validator/validator,validator/validator,takenspc/validator,takenspc/validator,validator/validator,validator/validator,takenspc/validator,validator/validator,takenspc/validator