Improve Tailscale documentation

[Bencaddyro]

Have you checked your request hasn't been already addressed in another issue?

• Yes

Is your content request an addition to an existing page?

• Yes, this is the page : https://developers.clever-cloud.com/doc/reference/reference-environment-variables/#tailscale-support
• No, the content is a new page/subject

Describe the content you'd like to see
A page for Tailscale documentation, (rather than a shady text bloc on general purpose env var)

Additional context
Improve dcumentation : application cannot use _ or (space) as they are relaced to _ by tailscale tooling and thus make tailscale failed to work

[juliamrch]

@Bencaddyro would you be up to take this issue?

[Bencaddyro]

😬 Not sure if i get enough bandwidth to do this right now
Maybe it will be more suitable to let the one's that release it to document it (aka @StevenLeRoux )

[juliamrch]

@StevenLeRoux are you up for the challenge?

[StevenLeRoux]

@juliamrch You bet I am!