Formatting issues on "How to modify an instance" documentation page

This issue is copied from here: https://github.com/canonical/multipass/issues/3675

## Summary

Description of documentation issue or suggestion
HTML tags are not escaped in this code block on [How to modify an instance](https://multipass.run/docs/modify-an-instance).

## Screenshot


## Comment thread

[sharder996](https://github.com/sharder996): @giuliazanchi Any ideas?

[giuliazanchi](https://github.com/giuliazanchi): Thanks for raising this issue, it looks like something changed on our backend as this was displayed correctly at some point in the past. I’ve removed the HTML formatting tags for now, so that it’s easier to read, but I’ll keep this issue open and assign it to myself to explore what went wrong and find a better solution.

[petesfrench](https://github.com/petesfrench): This issue is related to the web app, [multipass.run](https://multipass.run/), so should live under https://github.com/canonical/multipass.run/issues
@giuliazanchi @sharder996 I don't have the appropriate permissions on this repo to transfer the issue. Are you able to?

[ricab](https://github.com/ricab): Hi @petesfrench, I can transfer the issue, but multipass.run is not on the available options I get. Feel free to close this one and link/copy content if you prefer.

Start with the “How to modify an instance” page linked in the issue and inspect how its code block is rendered by the multipass.run site. Reproduce the unescaped HTML-tag display, then verify that the code block shows the intended text without formatting tags.

Written by the indexing model from the issue text.