Simplify docs for mac/linux/windows by consolidating the backend
dependencies (collaboration) docs into local-collaboration.md. Most
users building zed will not need to do this -- streamline them into
getting setup to build the zed client app first.
Release Notes:
- N/A
I’ve also updated the documentation in
`development\local-collaboration.md` and
`docs\src\development\windows.md`.
Testing collab on my Windows machine:

Release Notes:
- N/A
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Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>
This PR fixes the links to the "Backend dependencies" section from the
local collaboration docs.
We now provide links to the section in the platform-specific development
docs.
Release Notes:
- N/A
This PR fixes the links in the README to account for the changes in the
docs structure.
Also, somehow the README had gotten added with `\r\n` newlines, so I
changed it back to `\n` newlines.
Release Notes:
- N/A