docs: add deprecations to updating.md

[eschutho]

SUMMARY

Per #12566 this adds two sections to the updating.md file for notating deprecations vs breaking changes

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

[eschutho]

@garden-of-delete

[garden-of-delete]

Looks good to me. Thanks for adding this!

[codecov-io]

Codecov Report

Merging #12798 (1a94e7d) into master (55c8f9b) will decrease coverage by 2.90%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #12798      +/-   ##
==========================================
- Coverage   66.68%   63.77%   -2.91%     
==========================================
  Files        1021      488     -533     
  Lines       50008    30129   -19879     
  Branches     4905        0    -4905     
==========================================
- Hits        33346    19215   -14131     
+ Misses      16532    10914    -5618     
+ Partials      130        0     -130     

Flag	Coverage Δ
cypress	?
javascript	?
python	63.77% <ø> (-0.32%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/sql_validators/postgres.py	50.00% <0.00%> (-50.00%)	⬇️
superset/utils/cache.py	76.34% <0.00%> (-8.77%)	⬇️
superset/databases/commands/create.py	83.67% <0.00%> (-8.17%)	⬇️
superset/databases/commands/update.py	85.71% <0.00%> (-8.17%)	⬇️
superset/db_engine_specs/sqlite.py	90.62% <0.00%> (-6.25%)	⬇️
superset/databases/commands/test_connection.py	84.78% <0.00%> (-4.35%)	⬇️
superset/utils/celery.py	96.42% <0.00%> (-3.58%)	⬇️
superset/models/core.py	85.86% <0.00%> (-2.99%)	⬇️
superset/views/core.py	72.97% <0.00%> (-2.42%)	⬇️
superset/db_engine_specs/mysql.py	89.79% <0.00%> (-2.05%)	⬇️
... and 545 more

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[eschutho]

🏷 v1.0.1