Added more robust doucmentation around updates.

[Ferroin]

Summary

• Add a section to help users figure out which method they originally used to install Netdata.
• Update the description of how the manual update process works.
• Add a fallback command to help users deal with failures using the normal update process for the kickstart.sh and kickstart-static64.sh install methods.
• Don’t line wrap a long link that is causing problems with syntax highlighting in some editors when manually line-wrapped (it makes the whole document look like one big link).

Component Name

area/docs

Test Plan

n/a

[manos-saratsis]

@Ferroin if the dashboard is down this won't work but it's ok

[Ferroin]

Yeah, there’s unfortunately not any good way to do this without involving the dashboard or going through a long list of shell commands. I think it’s safe to assume that most users probably don’t actually need this command, but among those who do they are probably using default settings so it should work in most cases.

[joelhans]

Looking good! Just a few small requests.