docs: Security page in explanations has broken flowchart.

[MiroPalmu]

Please describe the question or issue you're facing with "Security - Mir v2.19.3-120-g9fee39b0ea documentation".

The security page in explanations displays following instead of rendering it (tested on Mozilla Firefox 134.0.2 and Chromium 132.0.6834.110 Arch Linux):

 %%{ init: { 'flowchart': { 'curve': 'monotoneY' } } }%%
flowchart
    shell((Mir-based Shell))
    vnc_server(VNC Server)
    vnc_client(VNC Client)
    osk(On-screen Keyboard)
    snapd(Snapd)
    operator_app(Operator App)
    user(User)
    display(Display)
    app(App)

    subgraph snap [Snap]
        vnc_server--input-->shell
        shell--screen content-->vnc_server

        osk--content/input-->shell
        shell--input-->osk
    end
    
    shell--contents/configuration--->display
    snapd--configuration-->shell
    display--visuals-->user
    operator_app--help message-->shell
    user--input events-->shell
    display--properties-->shell
    vnc_server<--vnc-->vnc_client
    app--window contents-->shell
    shell--input/window management-->app

    classDef boundary fill:none,stroke-dasharray: 5 5
    snap:::boundary

---

Reported from: https://canonical-mir.readthedocs-hosted.com/latest/explanation/security/

[Saviq]

Thanks @MiroPalmu, not sure where this breaks yet... we'll need to dig through.

The same approach is used on e.g. https://canonical-mir.readthedocs-hosted.com/stable/explanation/architecture/ and it works there...