WR340583, Add a dockerized nginx web server for serving built docs

Some parts of the documentation cannot be tested by opening the html
files with a browser. For instance search will not work in that case.

The solution is to serve the built files with a nginx web server
running in a docker container. Add a script to do this along with
instructions.

README.md

@@ -19,6 +19,10 @@ The first command only builds English. The second builds all translations
 
   manual-build/build-manual.sh TRANSLATIONS=en html
   manual-build/build-manual.sh html
+
+  manual-build/local-server.sh start
+  # check your changes in site served from the local server
+  manual-build/local-server.sh stop
 ```
 
 The built docs will be in the `build/html` directory (on your host machine).

local-server.sh

+#!/bin/bash
+#
+# Runs a dockerized nginx web server that will serve the Mahara manual
+# that has been built.
+#
+# This script will start the nginx container and publish it's port 80 to
+# ${CONTAINER_LISTEN_PORT} which will default to port 80 on the host machine.
+# If this does not suit you set an environment variable CONTAINER_LISTEN_PORT
+# with the port that you do want to use.
+
+CONTAINTER_NAME=${CONTAINTER_NAME:-mahara-nginx}
+CONTAINER_LISTEN_PORT=${CONTAINER_LISTEN_PORT:-80}
+
+cd $(dirname $0)/..
+
+if [[ "$1" == "stop" ]] ; then
+  docker container stop ${CONTAINTER_NAME}
+elif [[ "$1" == "start" ]] ; then
+  docker run --rm --name ${CONTAINTER_NAME} \
+    -p ${CONTAINER_LISTEN_PORT}:80 \
+    -v $(pwd)/build/html:/usr/share/nginx/html:ro \
+    -d nginx
+
+  echo "View the manual at http://localhost:${CONTAINER_LISTEN_PORT}/en/"
+else
+  echo "Usage $0 start|stop"
+fi