* Remove references to dedicated ROS distros
as final ROS 1 version, Noetic, is now EOL
* Redirect primary links to documentation landing page
as docs page is more up-to-date and pertinent for users
* Remove retired ROS blog
- https://www.ros.org/news/2020/01/ros-blog-retired.html
* Update OSRF URL redirect
* Update example image tag to rolling
to avoid docs from becoming stale
* Consolidate branding and dated references
* Update Q&A links to stackexchange given migration
- https://discourse.ros.org/t/planned-migration-of-ros-answers-and-gazebo-answers-to-robotics-stack-exchange/28068
- https://discourse.ros.org/t/new-static-archives-for-ros-and-gazebo-answers/41346
* Simplify cloning overlay source
* Simplify use of mixin setting
* Split runner and builder stages
as example to save on image size
as well as on build time using caching
* Simplify scripting for dependencies
* Lint use of ARGs
for readability of each stage
* Simplify example cache mount for apt
and update rosdep along with apt list
to ensure package index is fresh
* Update categories for ROS
to include additional relevant entries
* Shorten derivation script
* Use ros-core tag for minimal installer
* Stage example image sizes for demos
* Simplify naming
* Omit cacher from size table
to focus on primary targets
* Modify and mount custom apt config
accounting for included docker-clean default
* Simplify RUN directive for apt config
* Stage WIP edits
* Update package cache before cloning source
to avoid running rosdep update for each source change
as docker build --no-cache can still be used to force update
* Fix use of EOF in Dockerfile
* Simply RUN directives
* Expand bullet points about optimizations
* Expand upon runner vs installer comparison
* Linting
* Fix grammar and spelling
* Linting
* Rename stage in apt get example
while keeping with uniquely spelled noun
that is self descriptive yet unmistakable
* Comment on overwriting defaults to persist minimal cache