Update README with the latest bakery CLI instructions
Update README with the latest bakery CLI instructions

We renamed `fetch-html` command to `fetch-book` because we no longer
download the html.  It has been split into `fetch-book` -- downloading
the cnxml -- and `assemble-book` -- creating the single html.

Connexions/cnx-rulesets,Connexions/cnx-rulesets,Connexions/cnx-recipes,Connexions/cnx-recipes,Connexions/cnx-rulesets,Connexions/cnx-recipes,Connexions/cnx-recipes,Connexions/cte,Connexions/cnx-rulesets,Connexions/cnx-recipes,Connexions/cte