Improve wording, punctuation and capitalization in newbs_getting_started guide (...

Improve wording, punctuation and capitalization in newbs_getting_started guide (#4342)

* Improve wording, punctuation and capitalization in newbs_getting_started guide

Also add some links

* Update example build command output

Co-Authored-By: vomindoraan <vomindoraan@gmail.com>
* Replace occurrences of "layout" with "keymap"

Co-Authored-By: MechMerlin <30334081+mechmerlin@users.noreply.github.com>
* Explicitly instruct users to open an MSYS2 MinGW 64-bit terminal

* MSYS2 Console → MSYS2 MinGW

* Replace thin spaces with regular spaces