docs: fix table formating for multienv

[hanskhe]

what

Fixes a misformatted table in the docs under docs/custom-workflows.html#multiple-environment-variables-multienv-command.

why

• The text in the description column was broken over two rows, while the rest of the docs accepts long lines in one cell that wrap when displayed.
• The information on the fixed format expected appears to have been put into the table by mistake.

tests

I have tested the changes by running yarn run website:dev locally. Screenshots of before/after:

Before:

After:

This is my first PR for this repo, so please let me know if there are any issues, or if I have misunderstood anything.

[nitrocode]

Thank you for your contribution!