Release 6.2.0 polyhedron html

[sara-mokhtari]

Description

Add a What's New page for polyhedron models in v6.2.0. This branch was created directly from the branch https://github.com/SasView/sasview/tree/release_6.2.0.

Fixes #3971

The choice of the image and description can be discussed during a weekly meeting.

Review Checklist:

[if using the editor, use [x] in place of [ ] to check a box]

Documentation (check at least one)

• There is nothing that needs documenting
• [ x] Documentation changes are in this PR
• There is an issue open for the documentation (link?)

Installers

• There is a chance this will affect the installers, if so
  • Windows installer (GH artifact) has been tested (installed and worked)
  • MacOSX installer (GH artifact) has been tested (installed and worked)
  • Wheels installer (GH artifact) has been tested (installed and worked)

Licensing (untick if necessary)

• The introduced changes comply with SasView license (BSD 3-Clause)

[jellybean2004]

Hello @sara-mokhtari. Thank you for making this page. I pointed out one error in the html. After you correct that, this will be ready to merge.

I have also changed the target from main to release_6.2.0.

[krzywon]

@jellybean2004 - 2-6.html are now changed here. Was this intended or was there an issue with the rebase?

[jellybean2004]

@jellybean2004 - 2-6.html are now changed here. Was this intended or was there an issue with the rebase?

I rearranged the pages