DOC: Fix for side bar rendering on top of text issue

[harshvardhan2707]

Reference issue

closes #17532

What does this implement/fix?

Fixes the overlapping text and sidebar issue

Additional information

Screenshot of issue

[skip azp] [skip actions] [skip cirrus]

[tupui]

Thank you @harshvardhan2707, we will have a look shortly.

@j-bowhay that could be a good start 😃 (we could use this PR to go over things.) Just FYI @harshvardhan2707, we are on-boarding Jake as a new maintainer, nothing to be concerned on your side.

[j-bowhay]

Thanks @harshvardhan2707, this is pretty close just two changes are required:

1. You have changed the wrong matrix, the change should be on line 291 instead
2. The indented needs fixing eg. \mathbf{H} and begin{bmatrix} and subsequent lines should be on the same level of indentation. This will fix the rendering.

Two further things to keep in mind for the future:

• If possible try to skip CI that is not required (see https://docs.scipy.org/doc/scipy/dev/contributor/continuous_integration.html#skipping). In this case, as this is a doc-only change we don't need to run the whole test suite so you can add [skip azp] [skip actions] [skip cirrus] to the end of the commit message
• You have made your changes in your main branch. This is fine for this PR but it will cause you unnecessary headaches in the future if you wish to continue contributing

[j-bowhay]

Thanks @harshvardhan2707 LGTM, refguide failure is unrelated. Keep them coming!