Updated the VAE and GP regression notebook.

[zhenwendai]

Update the VAE and GP regression notebook with additional content.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-io]

Codecov Report

Merging #174 into develop will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           develop    #174      +/-   ##
==========================================
+ Coverage     88.1%   88.1%   +<.01%     
==========================================
  Files           79      79              
  Lines         4001    4002       +1     
  Branches       680     680              
==========================================
+ Hits          3525    3526       +1     
  Misses         308     308              
  Partials       168     168

Impacted Files	Coverage Δ
mxfusion/modules/gp_modules/svgp_regression.py	97.43% <100%> (+0.01%)	⬆️

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