fix(ci): use Docker network hostname for docs runner checkout

The act_runner and gitea containers share the git_default Docker
network. Use http://gitea:3000 (container DNS name) instead of
localhost, which resolves to the runner container itself.

docs/book.toml

@@ -2,6 +2,7 @@
 title = "Kindred Create Documentation"
 authors = ["Kindred Systems LLC"]
 language = "en"
+multilingual = false
 src = "src"
 
 [build]
@@ -11,6 +12,6 @@ build-dir = "book"
 default-theme = "coal"
 preferred-dark-theme = "coal"
 git-repository-url = "https://git.kindred-systems.com/kindred/create"
-git-repository-icon = "fas-code-fork"
+git-repository-icon = "fa-code-branch"
 additional-css = ["theme/kindred.css"]
 no-section-label = false