Final Editorial Updates to PSD

[Therecanbeonlyone1969]

• Updated Status to PSD
• Updated language to indicate the spec is no longer under active development
• Updated Dates throughout
• Updated Project Chair, Editors and Participants list
• Added missing Notice section to API spec
• Fixed broken links to github repo
• Replaced EEA with Ethereum where required

[Therecanbeonlyone1969]

@Ybittan @Kasshern @chaals please, approve ASAP. The PGB approved the PSD last month.