docs: toc and title fixes

#### summary of changes:

1. Add toc link to orphan doc.
1. Add page_title attributes where missing.

#### my approach in this PR
For the latter type of edit, there seems to be some inconsistencies in how each page is titled (nothing major, or very problematic from what I noticed). I didn't try to enforce any patterns - opting instead to start with a hopefully non-controversial, and certainly non-opinionated approach of using whatever h1 value was already present. Even there, though, there's a bit of inconsistency for pages that already had both an h1 and page_title -  some match h1 and page_title, whereas others deviate between the two.

#### consider for later
This doesn't really matter that much, but a style-guide might be useful. It doesn't have to be very elaborate. Examples of where some consistency could be enforced:

1. Decide whether h1 and page_title should match. If not, provide guidance on how they should differ.
1. For both or either of h1 and page_title, decide whether there's a pattern to follow. For example, I see existing patterns inconsistently applied like ...
  1. *SectionName*: *PageTopic* ... e.g. Templates: Builders
  1. *PageTopic* *SectionName* ... e.g. Chef Solo Provisioner
  1. *PageTopic* (no reference to *SectionName*) ... e.g. Configuration Templates