Improve Post Download thank you page

[magdmartin]

This issue follows the Heuristic Analysis done by asengupta on the forum

The proposition is to update the next step on the post-download thank you page for linux, macOs and windows with java to

• add a link to the documentation and relevant tutorials
• make the instructions for the installation process more granular with numbered steps or screenshots. See the macOs installation heuristic and process to circumvent macOS security warning. Those can be linked to specific documentation pages.
• remove the mention of the financial donation. It does not make sense to ask for financial support to first time user
• Reframe the community with an emphasis on support