Earthquake VM demo is broken - fix for instructions

Regarding this demo:
https://github.com/GoogleCloudPlatform/training-data-analyst/tree/master/courses/bdml_fundamentals/demos/earthquakevm

Fix instructions so

Instead of:
"cd training-data-analyst/courses/bdml_fundamentals"
Say:
"cd training-data-analyst/courses/bdml_fundamentals/demo/earthquakevm"

Open the earthquakevm demo linked in the issue and find the instructions containing the training-data-analyst/courses/bdml_fundamentals directory command. Update that command to point to demo/earthquakevm, then review the surrounding instructions to confirm the path is correct and consistent.

Written by the indexing model from the issue text.