DOC: wrong question marks in tutorial

[keithbriggs]

At https://pandas.pydata.org/docs/getting_started/intro_tutorials/index.html, things like

How to create plots in pandas

are not questions, so should not have a question mark.

(If it was "How do I create plots in pandas?", then it is a question, of course.)

[simonjayhawkins]

Thanks @keithbriggs for the report. PRs to fix most welcome.

[samrao1997]

take

[Sohlar]

Would you rather have periods or no punctuation?

[keithbriggs]

They are headings so they don't need punctuation.

[samrao1997]

Made PR and ready for review. I essentially just got rid of the question marks in the headings of those files.

[keithbriggs]

LGBT - sorry, LGTM.