Docs: avd-lab-guide.md - simplify the expression used to set LABPASSPHRASE

[mjbear]

Hello Arista Engineering people,

Mr. T asked me to put in issues before I open up PRs. I fully intend to open up PRs once suggestions are agreed upon. :sunglasses:

In both avd-lab-guide.md and cicd-basics.md there is an expression (piped shell commands) used to retrieve the LABPASSPHRASE from config.yaml. I have a suggestion that simplifies it greatly to exclusively an awk command.

Are you good with me submitting this as a PR?

Thank you!

[JulioPDX]

Oh yeah, that shortcut is not set in stone. Anything to simplify process is a good thing!

[mjbear]

Submitted PR #152

[JulioPDX]

Fixed in #152