typo flask requirements.txt in the getting started doc

[GabrielTruong]

In the Getting Started section, there is a typo like shown in the screenshot. It should be Flask instead of flask.

[jnsougata]

flask will do the work. It's case insensitive ig.

[GabrielTruong]

In some cases (Mac), it returns Bad Gateway. Is it a mac issue ?

[jnsougata]

In some cases (Mac), it returns Bad Gateway. Is it a mac issue ? works just fine for my linux. ig that's mac issue or I am installing wrong package...