Add known issue about jpeg8 pinning to README

For #210, fix a few other minor nits along the way

README.md

@@ -21,28 +21,29 @@ If this is your first time using Docker or any of the Jupyter projects, do the f
 2. Open the README in one of the folders in this git repository.
 3. Follow the README for that stack.
 
-## A visual overview of stacks
+## Visual Overview
 
 Here's a diagram of the `FROM` relationships between all of the images defined in this project:
 
-[![Image inheritance diagram](internal/inherit-diagram.png)](http://interactive.blockdiag.com/image?compression=deflate&encoding=base64&src=eJyFzLEOwjAMRdGdr7C6d0dURXRjZ0QIOY2LTNM4SsxQEP9Ow5YuXe87tnHSj5bxAZ8dgEQmr6gsHloIEjUia7MslgZ8Ob0P4jXxm5Z5n3sHV4eGXFtZMoz-8KSUmE6Xc1fdmt1f1EcwmKj2omRExnxXhCwm9jyhK9C6ZZd6DnOhypKNRcWlku9p81_c-BXmFDCOhVq37NC5ei2_P_VBd-Y)
+[![Image inheritance diagram](internal/inherit-diagram.png)](http://interactive.blockdiag.com/?compression=deflate&encoding=base64&src=eJyFzLEOwjAMRdGdr7C6d0dURXRjZ0QIOY2LTNM4SsxQEP9Ow5YuXe87tnHSj5bxAZ8dgEQmr6gsHloIEjUia7MslgZ8Ob0P4jXxm5Z5n3sHV4eGXFtZMoz-8KSUmE6Xc1fdmt1f1EcwmKj2omRExnxXhCwm9jyhK9C6ZZd6DnOhypKNRcWlku9p81_c-BXmFDCOhVq37NC5ei2_P_VBd-Y)
 
 ## Stacks, Tags, Versioning, and Progress
 
 Starting with [git commit SHA 9bd33dcc8688](https://github.com/jupyter/docker-stacks/tree/9bd33dcc8688):
 
-* Every folder here on GitHub has an equivalent `jupyter/<stack name>` on Docker Hub.
+* Nearly every folder here on GitHub has an equivalent `jupyter/<stack name>` on Docker Hub (e.g., all-spark-notebook &rarr; jupyter/all-spark-notebook).
 * The `latest` tag in each Docker Hub repository tracks the `master` branch `HEAD` reference on GitHub.
 * Any 12-character image tag on Docker Hub refers to a git commit SHA here on GitHub. See the [Docker build history wiki page](https://github.com/jupyter/docker-stacks/wiki/Docker-build-history) for a table of build details.
 * Stack contents (e.g., new library versions) will be updated upon request via PRs against this project.
 * Users looking to remain on older builds should refer to specific git SHA tagged images in their work, not `latest`.
 * For legacy reasons, there are two additional tags named `3.2` and `4.0` on Docker Hub which point to images prior to our versioning scheme switch.
 
-## Other Tips
+## Other Tips and Known Issues
 
 * `tini -- start-notebook.sh` is the default Docker entrypoint-plus-command in every notebook stack. If you plan to modify it in any way, be sure to check the *Notebook Options* section of your stack's README to understand the consequences.
 * Every notebook stack is compatible with [JupyterHub](https://jupyterhub.readthedocs.org) 0.5.  When running with JupyterHub, you must override the Docker run command to point to the [start-singleuser.sh](minimal-notebook/start-singleuser.sh) script, which starts a single-user instance of the Notebook server.  See each stack's README for instructions on running with JupyterHub.
 * Check the [Docker recipes wiki page](https://github.com/jupyter/docker-stacks/wiki/Docker-Recipes) attached to this project for information about extending and deploying the Docker images defined here. Add to the wiki if you have relevant information.
+* All stacks that derive from minimal notebook have the the conda jpeg package pinned to version 8 until https://github.com/jupyter/docker-stacks/issues/210 is resolved upstream.
 
 ## Maintainer Workflow