[TM-410] improve readability of Indigo website tables

Description

Problem: long "Description" lines in the expressions page in the Indigo website do not look good as "centered", however the short code cells look worse otherwise.

Solution: change the tables' cells text alignment to justified, but also change the style of code inside tables to look better.

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.

Stylistic guide (mandatory)

• My commits comply with the following policy.
• My code complies with the style guide.