Add detail about insert into compressed chunks

[Loquacity]

Description

Adds some detail about how data is inserted into compressed chunks. Also some very light editing. Based on info from the Community Slack chat, and timescale/timescaledb#4926

Links

Fixes #1832

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Subject matter expert (SME) review checklist

• Is the content technically accurate?
• Is the content complete?
• Is the content presented in a logical order?
• Does the content use appropriate names for features and products?
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Documentation team review checklist

• Is the content free from typos?
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  and have they been implemented?
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[github-actions]

Allow 10 minutes from last push for the staging site to build. If the link doesn't work, try using incognito mode instead. For internal reviewers, check web-documentation repo actions for staging build status. Link to build for this PR: http://docs-dev.timescale.com/docs-compression-inserts-lana

[jonatas]

Very good! I think @svenklemm is the main blessing we need in this PR!