Add Quick Start to Readme

[aguschin]

WIP to add Quick Start. 5 minutes video about MLEM will be based on this section.

[codecov]

Codecov Report

Merging #229 (1f763af) into main (926a843) will decrease coverage by 4.21%.
The diff coverage is 92.00%.

@@            Coverage Diff             @@
##             main     #229      +/-   ##
==========================================
- Coverage   89.16%   84.95%   -4.22%     
==========================================
  Files          74       77       +3     
  Lines        5059     5563     +504     
==========================================
+ Hits         4511     4726     +215     
- Misses        548      837     +289     

Impacted Files	Coverage Δ
mlem/api/commands.py	88.28% <50.00%> (+0.61%)	⬆️
mlem/cli/apply.py	94.73% <83.33%> (+0.98%)	⬆️
mlem/core/requirements.py	94.67% <88.23%> (-0.87%)	⬇️
mlem/cli/__init__.py	90.00% <100.00%> (+0.52%)	⬆️
mlem/cli/checkenv.py	100.00% <100.00%> (ø)
mlem/cli/deploy.py	94.59% <100.00%> (-0.15%)	⬇️
mlem/cli/main.py	76.44% <100.00%> (+1.68%)	⬆️
mlem/core/errors.py	91.52% <100.00%> (-3.60%)	⬇️
mlem/core/objects.py	88.44% <100.00%> (-3.19%)	⬇️
mlem/contrib/docker/helpers.py	50.00% <0.00%> (-50.00%)	⬇️
... and 33 more

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