chore(deps): bump docs/themes/docsy from e6d9477 to 77da7e4

Bumps [docs/themes/docsy](https://github.com/google/docsy) from `e6d9477` to `77da7e4`.
- [Release notes](https://github.com/google/docsy/releases)
- [Commits](google/docsy@e6d9477...77da7e4)

---
updated-dependencies:
- dependency-name: docs/themes/docsy
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>