message: docs: add missing docs for proposal-table
diff: @@ -5,7 +5,7 @@ authors = ["Nervos Core Dev <dev@nervos.org>"]
  edition = "2018"
  license = "MIT"
  # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
  -description = "TODO(doc): @zhangsoledad crate description"
  +description = "The CKB proposal table"
  homepage = "https://github.com/nervosnetwork/ckb"
  repository = "https://github.com/nervosnetwork/ckb"
  