Update asciinema on the landing page and add next steps

[MakisH]

At the bottom of the landing page, we currently have this recording from 2020, which is very outdated (preCICE v1, old tutorials):

This PR replaces that with a new recording:

The new recording:

• Replaces the perpendicular flap with the Quickstart, to:
  • Be able to show the concept of calling preCICE in a code
  • Clarify that the focus is on coupling your own code
  • Give an impulse on actually trying it as a next step
• Restricts the coupling time to two time windows, to fit the complete log in one terminal on the Solid side
• Has section markers
• Has a voiceover
• Hides a lot of the setup and teardown shown in the rpevious video
• Is still ~2min
• Uses asciinema v3

This PR also modifies the buttons to give clear next steps (closes #86), pointing to:

• https://precice.org/community-channels.html
• https://precice.discourse.group/c/what-is/9 ("is preCICE for me?" category)
• Quickstart

I will add the recording on the Quickstart page in another PR.

Why still asciinema?

• Very lightweight
• No cookies/tracking
• Some possibility for easy edits (in content, but also in color scheme, format, and more)
• Nice gimmick

How-to

Hoping to find this information when I want to update this video again:

• Get the tutorials from the distribution, as a file, and build released versions. Especially for the OpenFOAM adapter, build it in release mode, to hide excessive output.

• Start asciinema with a tmux session prepared:

  asciinema record --title "Quickstart" --command "tmux new-session \; split-window -h \; select-pane -L"  /path/to/file.cast

• Add markers as events later (or with the keyboard shortcut)

• Upload the recording

• Play and write down a script of what to say

• Cut and adjust synchronization in Audacity

• Enhance audio with Adobe podcast

• Upload to https://github.com/MakisH/served, to not pollute this repo, and to still have it served from GitHub

• Link with the recording

• Fine-tune the synching

Shortcuts:

• tmux move panes: Ctrl-m-o
• tmux detach session: Ctrl-m-d
• end recording: Ctrl-d

The way I did it this time, tmux detached also the asciinema session, but I could still use the recording.

[uekerman]

Very nice 🚀 Thank you!