[Docs] Add note about "Feather" to the IPC file format document

[asfimport]

The IPC file format is often referred to as Feather (especially in relation to Python and R), but beginners are confused because the word "Feather" does not appear on the IPC file format documentation.
https://arrow.apache.org/docs/format/Columnar.html#ipc-file-format

Note: This ticket was created as a result of a conversation with @kou on Twitter.
https://twitter.com/eitsupi/status/1547534742324920321

Reporter: SHIMA Tatsuya / @eitsupi
Assignee: SHIMA Tatsuya / @eitsupi

Related issues:

• [R] Add read/write_ipc_file separate from _feather (is related to)
• [R] Use .arrow as extension of IPC files of datasets (is related to)
• [Python] Use .arrow as extension for IPC file dataset (is related to)

PRs and other links:

• GitHub Pull Request #13693

_{Note: This issue was originally created as ARROW-17092. Please see the migration documentation for further details.}

[asfimport]

Kouhei Sutou / @kou:
Issue resolved by pull request 13693
#13693