- Fixed typos

[vishalbidwe]

Fixed typos issues151 :

• In docs/hardwaresimulation.rst observed wtih, now replaced with with.
• In docs/modules.rst observed interpeter, now replaced with interpreter.
• In docs/flask.rst observed happend now replaced with happened.
• In docs/_themes/README.rst observed drivative, now replaced with derivative.
• In docs/virtualenv.rst observed comamnd, now replaced with command.
• In docs/classes.rst observed classs, now replaced with class.
• In docs/classes.rst observed accross, now replaced with across.
• In docs/thebeginning.rst it does not contains terinal so no change required.