move diagnostics out of troubleshooting

[shawaj]

to make it easier to manage, probably makes sense to have a unified location for local diagnostics: https://github.com/NebraLtd/Helium-Guides/blob/main/docs/handy-guides/local-diagnostics.md

In the troubleshooting we can just link to this page:

• https://github.com/NebraLtd/Helium-Guides/blob/main/docs/indoor-hotspot/troubleshooting.md
• https://github.com/NebraLtd/Helium-Guides/blob/main/docs/outdoor-hotspot/troubleshooting.md

[salmanfarisvp]

@shawaj Agree 👍, Looks like you alredy made the changes or do I need to add anything?