[TM-410] fix Indigo website included lines

Description

Problem: Some lines included in the website from source files are not correct. The mistake was probably caused by an incorrect update after switching from 0-indexed to 1-indexed, so there are 2 issues:

• single lines are included still using 0-indexes
• some line indexes have not been updated, pointing at some wrong lines

Solution: update the line-including plugin to use 1-indexing for single lines and update the indexes in document inclusions that are incorrect.

Related issue(s)

https://issues.serokell.io/issue/TM-410

✅ Checklist for your Merge Request

Related changes (conditional)

• Tests (see short guidelines)

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

• Documentation

  • I checked whether I should update the docs and did so if necessary:
    • Root README and other README.md files
    • Haddock
    • docs/
  • I updated changelog files of all affected packages released to Hackage if my changes are externally visible.

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