DOC: Change "Convention for examples" to use Series name as ser instead of s

[Jakaho]

• [] closes DOC: Change "Convention for examples" to use Series name as ser instead of s  #53271 (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

[MarcoGorelli]

thanks @Jakaho ! there's a couple missing: def head and def plot, but the rest looks good!

[austinburnett]

thanks @Jakaho ! there's a couple missing: def head and def plot, but the rest looks good!

Hey @MarcoGorelli I believe I finished up the remaining changes at #53312.

[MarcoGorelli]

thanks @Jakaho ! there's a couple missing: def head and def plot, but the rest looks good!

Hey @MarcoGorelli I believe I finished up the remaining changes at #53312.

indeed, let's go with that one - @Jakaho for the future, if someone has already commented that they're working on an issue, please wait at least a week before taking over. Thanks anyway for your PR!