Attributes not rendering in navigation title

[lcawl]

Describe the bug

This was checked off in #160 but I'm still seeing this behaviour in the reference-content staging area:

Those values do exist in the docset.yml list of subs, for example:

subs:
...
  esql:   "ES|QL"

And are used in the files like this (e.g. in esql.md):

navigation_title: "{{esql}} reference"

Expected behavior

I expected substitutions to work within navigation titles.

Steps to reproduce

Check out the reference-content branch in our staging repo.
Go to the "Reference" > "Query languages" part of the tree.

Tooling

• docs-builder
• migration tooling
• I'm not sure

[Mpdreamz]

Either #458 fixes this too or this was already fixed but this is working in with the docs-builder build from #458