updated container docs

Author: krokicki

containers/README.md

@@ -0,0 +1,7 @@
+# Docker Containers
+
+This directory contains one subfolder for every Docker container used in the pipeline. Each container packages the entire system environment necessary for running that step of the pipeline, making the pipeline trivially portable across sytems.
+
+To easily rebuild these containers, install Docker and [maru](https://github.com/JaneliaSciComp/maru) and run `maru build`. 
+
+See the [Development docs](../docs/Development.md) for more information.

docs/Development.md

@@ -18,7 +18,7 @@ Commit as normal, then back at the root update the submodule commit pointer and
 
 ### Building containers
 
-All containers used by the pipeline have been made available on Docker Hub. You can rebuild these to make customizations or to replace the algorithms used. To build the containers and push to Docker Hub you can use [maru](https://github.com/JaneliaSciComp/maru), or manually:
+All containers used by the pipeline have been made available on Docker Hub. You can rebuild these to make customizations or to replace the algorithms used. To build the containers and push to Docker Hub you can install [maru](https://github.com/JaneliaSciComp/maru) and run `maru build`, or invoke Docker manually:
 
 #### Stitching container
 Container used for Spark-based stitching.