Request for better documentation about the dependency on `curl`

[ColinKennedy]

If you are running a version of curl that is out of date, plenary jobs spam Neovim to the point of being unusable with this message

Error executing luv callback:                                                                                                 
...al/.config/nvim/bundle/plenary.nvim/lua/plenary/curl.lua:273: post http://localhost:35831/exa.language_server_pb.LanguageSe
rverService/Heartbeat - curl error exit_code=2 stderr={ "curl: option --data-raw: is unknown", "curl: try 'curl --help' or 'cu
rl --manual' for more information" }                                                                                          
stack traceback:                                                                                                              
        [C]: in function 'error'                                                                                              
        ...al/.config/nvim/bundle/plenary.nvim/lua/plenary/curl.lua:273: in function '_user_on_exit'                          
        ...nal/.config/nvim/bundle/plenary.nvim/lua/plenary/job.lua:240: in function '_shutdown'                              
        ...nal/.config/nvim/bundle/plenary.nvim/lua/plenary/job.lua:46: in function <...nal/.config/nvim/bundle/plenary.nvim/l
ua/plenary/job.lua:37>

--data-raw was added in curl 7.43.0. It'd be nice if this repo mentions that curl is a dependency and has an expected version minimum.