Replace two videos (Data Portal and NMDC EDGE) with new ones hosted on YouTube

[eecavanna]

Tasks:

• Update https://docs.microbiomedata.org/tutorials/nav_data_portal.html to have video https://youtu.be/JV-8QWoL4aY embedded into it, in place of the video currently embedded in the "Navigating the Data Portal" section of the page
• Update https://docs.microbiomedata.org/tutorials/run_workflows.html to have video https://youtu.be/Z5Oq7BXo43k embedded into it, in place of the video currently embedded in the "NMDC EDGE QuickStart" section of the page

Ticket #151 may be in reference to one of these videos. I don't know.

CC: @jkelliher-github

I'll do those tasks now.