clarify bundle installation

[dbu]

the composer command should not fail when this page is somebody's entry point on how to set up HTTPlug

[Nyholm]

I do not understand this line. Are you trying to say something like:
"If composer fails to install the bundle, you have to specify which HTTP..."

[Nyholm]

Oh, I see. how about:

" If you have not already installed a HTTP client, you need to specify the client when installing the bundle. See [link] for a list of available clients"

[dbu]

no, if you installed php-http/httplug and its requirements already, you can just add the bundle. any idea how to say this better?

[fbourigault]

I would say:

$ composer require php-http/httplug-bundle <your client adapter choice>
You can find an available client adapter here(link to the right page). However you can omit the client adapter if you already have one installed.

EDIT: we should probably suggest a suitable client implementation such as guzzle6 as it does not require more dependencies (message, factory, etc...). I also suggested to tell user to require the adapter unless they have one as I think most user workflow, in a Symfony project, is to require the bundle which depends on the library.

[dbu]

updated. i wanted to include something in the command line because people tend to think they know how it works and just copy the package name without reading the fluff around it...