Pattern page - add navigation for other patterns on the same level

[lucijanblagonic]

Currently, there is no easy way to jump between patterns on the same level. Person has to go to the "Patterns" page, scroll through the long page and go to another pattern.

Adding dropdown to the Patterns navigation item would help with discoverability of other patterns for people who land on the pattern page directly, and improve usability when switching between patterns. Previously, all the patterns were on the same page so a person could use the left navigation to move between patterns.

This should also be applied to Practices as well to ensure consistency.

[charmarkk]

IRC convo from APG meeting on 5/24:

[13:31] Matt_King: i love this suggestion

[13:31] Matt_King: belongs in the other repo, solved on template level

[13:33] group: seems like a good plan

[13:34] Matt_King: seems like a straightforward design enhancement

[13:35] Matt_King: there's something similar in the WAI template, previous forward with a select box as
well

[13:35] love having select drop down

[13:35] Matt_King: can Isaac work on this?

[13:35] Rich_Noah: we'll get the issue into the backlog and schedule it

[13:36] Matt_King: not urgent!

[13:36] Matt_King: could be a Q3 change

[mcking65]

Work in progress in w3c/aria-practices#2535