Create documentation outlining the differences of running GitLab in a Memory Constrained Environment

In our efforts to reduce the memory footprint when running GitLab in a memory constrained environment, the GitLab installation and configuration will make some intelligent choices about how to best run in the target environment. We foresee a few potential scenarios here:

• Silent and efficient configuration decisions based on known constraints
• Optimal configurations (best guess)
• User configuration selection
• Potentially offering deactivation of expensive and unused features (this option is still being explored in Product Management).

We will need to provide documentation similar to the Running on a Raspberry Pi with details about changes to a standard installation and/or additional recommendations

Grading

• We have a 4GB environment, review/revise
• Write up a section/guidance for 3GB
• Write up a section/guidance for 2GB