Update quality declaration documents

[christophebedard]

• Switch from "ROS2" to "ROS 2"
• Update libyaml version from 0.1.8 (not 0.18) to 0.2.5
• Change "Github" to "GitHub"
• Apply one-sentence-per-line rule in some places
• Rephrase some sentences

[clalancette]

I'm going to go ahead and merge without CI, since this doesn't touch any code.