Pass --module-version and --root-url parameters to jazzy (apple…

…#700)

* Pass `--module-version` and `--root-url` parameters to `jazzy`

### Motivation:

It would be good if the API document was distributed as a docset that can be installed in Dash, like [Yams](https://www.jpsim.com/Yams/).

### Modifications:

Pass `--module-version` and `--root-url` parameters to `jazzy`.

### Result:

Jazzy generates docsets and add "Install in Dash" link to `index.html`.

* Apply review: Avoid appending `args`

scripts/generate_docs.sh

@@ -71,7 +71,9 @@ for module in "${modules[@]}"; do
 done
 
 for module in "${modules[@]}"; do
-  args=("${jazzy_args[@]}"  --output "$root_path/docs/$version/$module" --module "$module")
+  args=("${jazzy_args[@]}"  --output "$root_path/docs/$version/$module" --module "$module"
+        --module-version $version
+        --root-url "https://apple.github.io/swift-nio/docs/$version/$module")
   if [[ -f "$root_path/.build/sourcekitten/$module.json" ]]; then
     args+=(--sourcekitten-sourcefile "$root_path/.build/sourcekitten/$module.json")
   fi