🎨 Simplify read function and datasets calls

[sunnyosun]

• Updated example datasets call in tutorials
• Simplified read_fcs

Tests won't pass if docs directories are empty, so I added back the placeholder notebooks in notes, guides and examples.

[github-actions[bot]]

🚀 Deployed on https://62efc2efa304d71039762d4b--pytometry.netlify.app

[codecov-commenter]

Codecov Report

Merging #15 (f2cacd2) into main (9dcac41) will decrease coverage by 0.66%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #15      +/-   ##
==========================================
- Coverage   72.93%   72.27%   -0.67%     
==========================================
  Files           8        8              
  Lines         351      339      -12     
==========================================
- Hits          256      245      -11     
+ Misses         95       94       -1     

Impacted Files	Coverage Δ
pytometry/read_write/_readfcs.py	100.00% <100.00%> (+6.25%)	:arrow_up:

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