DOC: Updated tutorials.rst, added 3 recent video tutorials

[tommyod]

I have made the following changes to tutorials.rst (found here):

• Updated the version of the pandas-cookbook from v0.1 to v0.2.
• Added an introductory paragraph to the tutorial series by @TomAugspurger.
• Added 3 recent, high-quality video tutorials (Youtube).

[codecov]

Codecov Report

Merging #19748 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #19748      +/-   ##
==========================================
- Coverage    91.6%   91.58%   -0.03%     
==========================================
  Files         150      150              
  Lines       48862    48862              
==========================================
- Hits        44762    44750      -12     
- Misses       4100     4112      +12

Flag	Coverage Δ
#multiple	89.95% <ø> (-0.03%)	⬇️
#single	41.75% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/plotting/_converter.py	65.22% <0%> (-1.74%)	⬇️

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[TomAugspurger]

Thanks. I'm surprised we didn't already link to Brandon Rhode's tutorial.