Getting started instructions to install python should probably be consistent with tutorial docs

[karrtikr]

Currently we have the getting started experience, which for example in windows, points users to the windows store python. However our tutorial https://code.visualstudio.com/docs/python/python-tutorial#_install-a-python-interpreter is a little different. https://code.visualstudio.com/docs/python/python-tutorial#_install-a-python-interpreter is also linked to in some of our prompts the extension uses, to recommend users from where to install python.

cc/ @luabud

[karrtikr]

Note Windows store may not be available for Windows 8, so it's probably best to point to python.org.