Add subpages to global nav

[theecrit]

What are you submitting?

Place an x in the appropriate bracket:

• Bug (something's broken)
• Feature request or improvement
• Content update
• Question
• Other

Description

Our current global nav is a single-level menu, but we now have subpages in some sections that deserve to be surfaced in the menu. Specifically:

About

• How we work
• Bylaws (per Embed Bylaws into a dedicated page #222)

Calendar

• Suggest a speaker

Considerations

• Needs to work on mobile
• Ideally, top-level item is clickable and leads to the main landing page, with subpages listed as level 2 (may depend on Bootstrap functionality

Thank you!

• Please document your design and tech decisions in your pull request so others can follow along and understand why we've made the decisions we have.
• If you'd like feedback, input, or help, share your thoughts or question in this issue's comments.