Added script to generate site into branch asf-site
diff --git a/.circleci/update-asf-site.sh b/.circleci/update-asf-site.sh
new file mode 100755
index 0000000..2d6e0cf
--- /dev/null
+++ b/.circleci/update-asf-site.sh
@@ -0,0 +1,31 @@
+#!/bin/bash
+# Generates, commits, and pushes the Zipkin documentation site
+# into the `asf-site` branch
+
+set -xeuo pipefail
+
+# Bail out if there are any changes in git
+if ! git diff-index --quiet HEAD --; then
+ echo 'Uncommitted changes exist. Bailing out.'
+ exit 1
+fi
+
+# Create a temporary directory in a way that works on both Linux and macOS.
+# See https://unix.stackexchange.com/questions/30091/fix-or-alternative-for-mktemp-in-os-x
+readonly builddir="$(mktemp -d 2>/dev/null || mktemp -d -t 'mytmpdir')"
+
+# We'll add the current commit sha to the commit message on the target branch
+readonly master_sha="$(git rev-parse --short HEAD)"
+
+# Grab the target branch, delete the existing files so we can do a clean build
+git clone --branch asf-site -- git@github.com:openzipkin/openzipkin.github.io "$builddir"
+rm -rf "${builddir:?}/*"
+
+# Generate the site
+bundle exec jekyll build --destination "$builddir"
+
+# Commit and push the content
+cd "$builddir"
+git add .
+git commit -m "Generated site from ${master_sha}"
+git push
