Following up for #123

[ktock]

• a1fe957 : this flag name is confusing because we're not using QEMU (while relying on the protocol). so rename it to net=socket
• 6b8965e : some descriptions are confusing because we can't use gvisor-tap-vsock as-is but we need to use c2w-net or c2w-net-proxy for networking of containers on wasm.
• 38ab1f0 : mention about forbidden headers which are controlled by the browser and can't be changed from the container and the proxy. These headers added by the container will be modified or ignored by the browser.
• ff03e50 letting browser set this allows more requests becoming simple requests that reduces CORS preflight and the container can access many more sites. (this behaviour is the same as chrome that silently drops User-Agent header from Fetch requests https://developer.mozilla.org/en-US/docs/Glossary/Forbidden_header_name )