adding github workflow to render docs and lint

This should be equivalent to the .travis-ci workflow, but run
in GitHub actions. I am using the exact commit of the v1 release,
as that is considered safer practice than the tag/release itself.

Signed-off-by: vsoch <vsoch@users.noreply.github.com>

.github/workflows/docs-and-linting.yml

@@ -0,0 +1,49 @@
+name: Render and Lint Documentation
+
+on:
+  pull_request:
+    branches_ignore: []
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go: ['1.10', '1.11', '1.12']
+
+    name: Documentation and Linting
+    steps:
+
+      - uses: actions/checkout@v2
+        with:
+          path: go/src/github.com/opencontainers/image-spec
+
+                               # commit for v1 release
+      - uses: actions/setup-go@0caeaed6fd66a828038c2da3c0f662a42862658f
+        with:
+          go-version: ${{ matrix.go }}
+
+      - name: Render and Lint
+        env:
+          GOPATH: /home/runner/work/image-spec/image-spec/go
+        run: |
+          export PATH=$GOPATH/bin:$PATH
+          docker pull quay.io/oci/pandoc:1.17.0.3-2.fc25.x86_64
+          cd go/src/github.com/opencontainers/image-spec
+          make install.tools
+          go get -u github.com/alecthomas/gometalinter
+          gometalinter --install
+          go get -t -d ./...
+          ls ../
+          make
+          make .gitvalidation
+          make lint
+          make check-license
+          make test
+          make docs
+
+      - name: documentation artifacts
+        uses: actions/upload-artifact@v2
+        with:
+          name: oci-docs
+          path: go/src/github.com/opencontainers/image-spec/output

Makefile

@@ -4,14 +4,13 @@ export GO15VENDOREXPERIMENT
 DOCKER ?= $(shell command -v docker 2>/dev/null)
 PANDOC ?= $(shell command -v pandoc 2>/dev/null)
 
-OUTPUT_DIRNAME	?= output/
+OUTPUT_DIRNAME	?= output
 DOC_FILENAME	?= oci-image-spec
 
 PANDOC_CONTAINER ?= quay.io/oci/pandoc:1.17.0.3-2.fc25.x86_64
 ifeq "$(strip $(PANDOC))" ''
 	ifneq "$(strip $(DOCKER))" ''
 		PANDOC = $(DOCKER) run \
-			-it \
 			--rm \
 			-v $(shell pwd)/:/input/:ro \
 			-v $(shell pwd)/$(OUTPUT_DIRNAME)/:/$(OUTPUT_DIRNAME)/ \
@@ -107,11 +106,11 @@ img/%.png: img/%.dot
 	dot -Tpng $^ > $@
 
 
-# When this is running in travis, it will only check the travis commit range
+# When this is running in GitHub, it will only check the commit range
 .gitvalidation:
 	@which git-validation > /dev/null 2>/dev/null || (echo "ERROR: git-validation not found. Consider 'make install.tools' target" && false)
-ifdef TRAVIS_COMMIT_RANGE
-	git-validation -q -run DCO,short-subject,dangling-whitespace
+ifdef GITHUB_SHA
+	git-validation -q -run DCO,short-subject,dangling-whitespace -range $(GITHUB_SHA)..HEAD
 else
 	git-validation -v -run DCO,short-subject,dangling-whitespace -range $(EPOCH_TEST_COMMIT)..HEAD
 endif