Merge branch 'book' into 'master'

Fix book recipe compilation, add mdbook to CI

See merge request redox-os/redox!2310

config/x86_64/ci.toml

@@ -164,6 +164,7 @@ lua-compat-53 = {}
 luajit = {}
 luarocks = {}
 lz4 = {}
+mdbook = {}
 mednaffe = {}
 mednafen = {}
 mesa = {}

recipes/other/book/recipe.toml

@@ -3,6 +3,9 @@ git = "https://gitlab.redox-os.org/redox-os/book.git"
 shallow_clone = true
 [build]
 template = "custom"
+dev-dependencies = [
+    "host:mdbook"
+]
 script = """
 dir="${COOKBOOK_STAGE}/usr/share/book"
 mkdir -pv "${dir}"