Update Http-server doc with new location of getHttpOperationsFromSpec (#1820)
Update Http-server doc with new location of getHttpOperationsFromSpec (#1820)

* Update Http-server doc with new location of getHttpOperationsFromSpec
In #1009 the getHttpOperationsFromSpec moved to the prism-cli package. The documentation needs to be updated accordingly

* Update packages/http-server/README.md

Co-authored-by: Thomas Pytleski <892369038dc46395387e316e258e266f509e92fa@gmail.com>
stoplightio/prism,stoplightio/prism,stoplightio/prism