Bump sdoc from 2.4.0 to 2.6.0

Bumps [sdoc](https://github.com/zzak/sdoc) from 2.4.0 to 2.6.0.
- [Release notes](https://github.com/zzak/sdoc/releases)
- [Changelog](https://github.com/zzak/sdoc/blob/master/CHANGELOG.md)
- [Commits](https://github.com/zzak/sdoc/commits)

---
updated-dependencies:
- dependency-name: sdoc
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -329,7 +329,7 @@ GEM
       sprockets (> 3.0)
       sprockets-rails
       tilt
-    sdoc (2.4.0)
+    sdoc (2.6.0)
       rdoc (>= 5.0)
     selenium-webdriver (4.7.1)
       rexml (~> 3.2, >= 3.2.5)