docs / alerting / fundamentals / templates

[tonypowa]

This PR :

• moved the "template" page into a new folder named "templates"
• renamed the above page so it becomes the index page of that folder
• created a sub-page "label-annotations" which basically contains the content from the existing labels and annotations page plus some elaboration on the templating part

TODO:

• test with make docs
• check if tree structure and file names are correct
• check if front matter is correct

[tonypowa]

will add the notif template part to this PR . ill let you know @brendamuir

[tonypowa]

hi @brendamuir I have applied the changes we discussed the other day
i will test how it looks locallyy and let you know