Add opnfvdocs build container

Currently, rst files only can be built in opnfvdocs project's CI
pipeline and feature projects can not verify this before submitting doc
files. Feature project can use this container to build its docs without
installing any docs tools.

JIRA: DOCS-183

Change-Id: I715d19d24da776d76e509309c9010d4072e6f4f8
Signed-off-by: Julien <zhang.jun3g@zte.com.cn>

1 files changed, 28 insertions, 0 deletions

diff --git a/docker/README.md b/docker/README.md
new file mode 100644
index 000000000..c7b119c1b
--- /dev/null
+++ b/docker/README.md
@@ -0,0 +1,28 @@
+# OPNFVDoc tool readme
+------------------------
+
+This docker container is used for building OPNFV docs from **rst** format files for each feature
+project. The output is just like contents in [opnfvdocs](http://docs.opnfv.org/) website. You can
+review the contents through web browser. Currently *PDF* output is not good enough and it will make
+the container image size 3x larger. PDF output format is not supported in this release.
+
+# Usage
+
+* The default build is *html*, you can run:
+```
+docker run -it --rm -v ./some-opnfv-repo:/docs -v /tmp/output:/output \
+     opnfv/opnfvdocs
+```
+
+* Then if you want to build epub, etc you could pass it as an arg:
+```
+docker run -it --rm -v ./some-opnfv-repo:/docs -v /tmp/output:/output \
+     -e build=epub opnfv/opnfvdocs
+```
+
+## env parameters
+* build: [html | singlehtml | epub]
+
+## two directory parameters
+* /docs: **mandatory**, used for source files
+* /output: **optional**, used for storing the built result