installing-using-pip: Update command output

[bhrutledge]

As noted in in #928 (comment), there are few places in that document where the command and its output are shown in a single code-block, but with no distinction between them, which might lead folks to thinking that pip 9.0.1 ... is a command to execute. If the output of a command is valuable, I recommend putting it into a separate .. code-block:: text.

Also, the output from the pip --version is quite old. Let's take this opportunity to update it.

[webknjaz]

Honestly, I think it's a wrong solution — it's natural to see the console output for as long as the prompt is present and the correct lexer for sessions is set.