Add a period in the "Be a bridge" section of the Editorial Style Guide

### Summary
The sentence in the "Be a bridge" section of the Editorial Style Guide currently lacks a period at the end.

### Suggested Fix
Add a period at the end of the final sentence in that section to improve grammatical consistency.

### File
`guides/editorial-style-guide.md`

### Impact
This is a minor editorial correction that improves readability and consistency.