Add vale to continuous integration

Author: jseldess

ci/Dockerfile

@@ -21,6 +21,7 @@ RUN apk add --update \
     zlib \
     zlib-dev \
   && GOBIN=/usr/local/bin go get -u github.com/cockroachdb/htmltest \
+  && wget -O- https://github.com/errata-ai/vale/releases/download/v0.11.2/vale_0.11.2_Linux_64-bit.tar.gz | tar -xzC /usr/local/bin vale \
   && pip install --upgrade awscli \
   && cd /tmp/bundler && bundle install && rm -rf /tmp/bundler \
   && apk --purge del \

ci/builder

@@ -3,7 +3,7 @@
 set -euo pipefail
 
 image=cockroachdb/docs-builder
-version=${COCKROACH_DOCS_BUILDER_VERSION:-20180311-222618}
+version=${COCKROACH_DOCS_BUILDER_VERSION:-20180529-163433}
 
 root=$(cd "$(dirname "$0")" && pwd)
 repo_root=$root/..

ci/pull-request

@@ -29,5 +29,8 @@ curl \
   --data "{\"body\": \"http://cockroach-docs-review.s3-website-us-east-1.amazonaws.com/$BUILD_VCS_NUMBER/\"}" \
   "https://api.github.com/repos/cockroachdb/docs/issues/$BUILD_BRANCH/comments"
 
-# Step 4. Run htmltest, but skip checking external links to speed things up.
+# Step 4. Run vale, but don't fail the build if it reports errors.
+run vale --no-wrap v2.1 || true
+
+# Step 5. Run htmltest, but skip checking external links to speed things up.
 run htmltest --skip-external