Update Path.lagda.md

[AndyShiue]

chore: Fix typo. NOAUTHOR

Description

There is a typo that uses "a" where "an" should be used

Checklist

Before submitting a merge request, please check the items below:

• I've read the contributing guidelines.
• The imports of new modules have been sorted with support/sort-imports.hs.
• All new code blocks have "agda" as their language.

If a commit affects many files without adding substantial content, and
you don't want your name to appear on those pages (for example, treewide
refactorings or reformattings), start the commit message with chore:
or include the word NOAUTHOR anywhere.

[plt-amy]

Thank you!