Replaced commit() with flush() in documentation.

[dhiganthrao]

Following up on a conversation with @AbhinavTuli and @mynameisvinn, I am creating a pull request to replace all mentions of commit() with flush(), as the commit() method is deprecated. Please let me know if I've missed anything or need to further replace anything else. Thank you!

[github-actions]

Locust summary

Git references

Initial: c0317c5
Terminal: 7e5e40e

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[codecov]

Codecov Report

Merging #604 (db717c6) into master (c0317c5) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #604   +/-   ##
=======================================
  Coverage   89.25%   89.25%           
=======================================
  Files          53       53           
  Lines        3881     3882    +1     
=======================================
+ Hits         3464     3465    +1     
  Misses        417      417           

Impacted Files	Coverage Δ
hub/api/dataset.py	89.34% <100.00%> (+0.02%)	⬆️

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[AbhinavTuli]

Looks great. Thanks for the quick PR! I think I missed out on mentioning the changes to the examples folder (you can ignore the "old" subfolder there). Should be good to merge once you've replaced those as well.

[mynameisvinn]

@dhiganthrao Could you log a warning when Dataset.commit is invoked?

[dhiganthrao]

Sure! I have done the same, please check and let me know if there are any errors.

[AbhinavTuli]

Looks good to me. @mynameisvinn we can let this warning remain for now and remove it once version control is out of alpha.