doc, nixos/doc: include roboto font

Roboto was already set as the font for the manuals,
but without a way to get it, so people who didn't
happen to have it installed saw their default font

doc/doc-support/package.nix

@@ -13,6 +13,7 @@
   writeShellScriptBin,
   nixpkgs ? { },
   markdown-code-runner,
+  roboto,
 }:
 
 stdenvNoCC.mkDerivation (
@@ -98,6 +99,8 @@ stdenvNoCC.mkDerivation (
       mv out "$dest"
       mv "$dest/index.html" "$dest/manual.html"
 
+      cp ${roboto.src}/web/Roboto\[ital\,wdth\,wght\].ttf "$dest/Roboto.ttf"
+
       cp ${epub} "$dest/nixpkgs-manual.epub"
 
       mkdir -p $out/nix-support/

doc/style.css

@@ -486,3 +486,8 @@ div.appendix .variablelist .term {
         font-weight: 400;
     }
 }
+
+@font-face {
+    font-family: Roboto;
+    src: url(Roboto.ttf);
+}

nixos/doc/manual/default.nix

@@ -160,6 +160,8 @@ rec {
           ./manual.md \
           $dst/${common.indexPath}
 
+        cp ${pkgs.roboto.src}/web/Roboto\[ital\,wdth\,wght\].ttf "$dst/Roboto.ttf"
+
         mkdir -p $out/nix-support
         echo "nix-build out $out" >> $out/nix-support/hydra-build-products
         echo "doc manual $dst" >> $out/nix-support/hydra-build-products