[feature request]: support to automatically appent <html>, <head>, <body> #1864
Description
We use cheerio to handle lots of html，and found that htmlparser2 is much faster than parse5 which cheerio used by default, and saving about 40% cpu usage when handling lots of html. But in parse5, it will automatically append <html>, <head>, <body> if those tags are not included in the html input, we depend on this behavior.
Consider to add an options to support this feature?