[docs] numerous FAQ updates

[benmccann]

• added links to various open issues
• moved info about reading package.json into its own FAQ. it seems unrelated to the question it was included in
• remove file system access faq since i'm not sure it is frequently asked. i've never seen someone hit it
• updated client-side FAQ to account for SSR lifecycle no-ops in newest version of Svelte
• updated links to point to new sveltesociety website

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