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GH-37756: [Format][Docs] Document IPC Compression (#43950)

### Rationale for this change

There is no information about buffer compression of the record batch IPC
message in the format docs
(https://arrow.apache.org/docs/format/Columnar.html).

### What changes are included in this PR?

New paragraph is added with basic information about buffer compression
in IPC.

### Are these changes tested?

No, it is only documentation update.

### Are there any user-facing changes?

No, only documentation update.
* GitHub Issue: #37756

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Co-authored-by: Ian Cook <ianmcook@gmail.com>
Co-authored-by: Sutou Kouhei <kou@cozmixng.org>
Co-authored-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>