installation doc issues

[robsimmonds]

Have marked up some problems and suggestions in these pdfs.

Installation — CARTA Controller 3.0.0-beta.3 documentation.pdf
Step-by-step instructions for CentOS 8 — CARTA Controller 3.0.0-beta.3 documentation.pdf
Step-by-step instructions for Ubuntu 20.04.2 (Focal Fossa) — CARTA Controller 3.0.0-beta.3 documentation.pdf

[confluence]

A partial list of fixes (apart from typos, missing packages, etc.):

• Add manual line breaks to long lines in code samples so that they don't get malformed in the PDF
• Simplify the RHEL/CentOS instructions as much as possible to make them more closely aligned with the Ubuntu instructions
• Add an overview section to the installation page which explains what the components are and what OSes are supported, and links to the step-by-step instructions
• Revise or remove the starting paragraph on the landing page

[confluence]

Bumping this. We really should revise the more general installation page so that people stop trying to use it as a step-by-step tutorial. The links to the detailed instructions should be more prominent, and not inside the backend section. All literal code snippets on that page should be clearly marked as examples and not complete instructions.