Add instructions so users can add notebooks to Jupyter lite deployments

[mcbarton]

Description

Please include a summary of changes, motivation and context for this PR.

Thie PR updates Emscripten-build-instructions.md to include instructions so user can add own notebooks to own deployments

Fixes # (issue)

Type of change

Please tick all options which are relevant.

• Bug fix
• New feature
• Requires documentation updates

Testing

Please describe the test(s) that you added and ran to verify your changes.

Checklist

• I have read the contribution guide recently

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.96%. Comparing base (b93db9c) to head (46abcef).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #435   +/-   ##
=======================================
  Coverage   70.96%   70.96%           
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  Files           9        9           
  Lines        3541     3541           
=======================================
  Hits         2513     2513           
  Misses       1028     1028           

[vgvassilev]

LGTM!