Update installation code fence

[kianmeng]

List of changes:

• add missing language for code fence
• use python -m pip installation method

[jbednar]

Specifying the language looks useful, thanks! What's the reasoning behind using python -m pip instead of just pip? It doesn't seem to me like most users would need the more complicated version.

[kianmeng]

@jbednar See https://snarky.ca/why-you-should-use-python-m-pip/

[jbednar]

Thanks!

[kianmeng]

:partying_face: :partying_face: :partying_face: :partying_face: :partying_face: