Remove unknown multilingual directive from book.toml.

Fix and improve mdbook related.

Signed-off-by: Jason Volk <jason@zemos.net>

book.toml

@@ -5,7 +5,6 @@ authors = [
 ]
 description = "Tuwunel, a high performance successor to Conduit and Conduwuit"
 language = "en"
-multilingual = false
 src = "docs"
 title = "Tuwunel One"
 text-direction = "ltr"
@@ -15,7 +14,9 @@ build-dir = "public"
 create-missing = true
 extra-watch-dirs = [
 	"debian",
+	"docker",
 	"docs",
+	"rpm",
 ]
 
 [rust]
@@ -24,7 +25,7 @@ edition = "2024"
 [output.html]
 git-repository-url = "https://github.com/matrix-construct/tuwunel"
 edit-url-template = "https://github.com/matrix-construct/tuwunel/edit/main/{path}"
-git-repository-icon = "fa-github-square"
+git-repository-icon = "fab-github"
 
 [output.html.search]
 limit-results = 15