bug#54690: Cookbook: packagin example is missing use of input or output

[Hartmut Goebel <h.goebel@crazy-compilers.com>]

Hi,

the extended Packaging example in the Cookbook 
https://guix.gnu.org/cookbook/en/html_node/Extended-example.html is 
missing examples how to use the inputs and outputs in phases (new style).

Also the example seems to not use g-exps, as it still uses the backquote:

       (arguments
        `(#:tests? #true                         ; Run the test suite (this is the default)
          #:configure-flags '("-DUSE_SHA1DC=ON") ; SHA-1 collision detection
          #:phases
          (modify-phases %standard-phases
            (add-after 'unpack 'fix-hardcoded-paths

Also the „Inputs“ and „Outputs“ sections do not show an example. This 
could be copied from above. Maybe it is even better to show how to use 
inputs and outputs in phases here - and not have it in the example above 
- as I did go directly to the „Inputs“ section.

-- 
Regards
Hartmut Goebel

| Hartmut Goebel          | h.goebel@crazy-compilers.com               |
| www.crazy-compilers.com | compilers which you thought are impossible |