Update doc links within the extension

[melissahenderson]

Webmonetization.org currently contains the documentation within the /docs path. For example, https://webmonetization.org/docs/intro/sending-payments/.

In the new doc set, the /docs path is no longer necessary. All links within the extension that point to user docs will need to be updated when the new doc set is ready to go live (TBD).

Tasks look something like this:

• [ ] Coordinate with team before doc set is published
• [ ] Provide a list of the updated URLs
• [ ] Work with Sarah to set up redirects from the old links used in the extension to the new links
• [ ] Publish new doc set

We'll need to keep the redirects for some time (until there's only a small population of individuals using the version of the extension w/ the old links).

[sidvishnoi]

There's only one link from extenstion to docs as of yet:

• https://github.com/interledger/web-monetization-extension/blob/8b3c33f036e9f2eb001557c9a27ba8e00d0dc8ed/src/popup/components/ConnectWalletForm.tsx#L469