Remove deprecated class map generator documentation

[arueckauer]

This PR removes the documentation of the ZF 2 script bin/classmap_generator.php, which never was part of this component.

Instead the usage of Composer for autoloading is suggested and a reference to the migration guide added.

[froschdesign]

@weierophinney @michalbundyra
Is the Zend\Loader\ClassMapAutoloader class deprecated or can this class be marked as deprecated?

[weierophinney]

Honestly, this entire package can likely be deprecated.

The only places it is used anywhere within ZF are:

• zend-modulemanager (which uses the ModuleAutoloader as a fallback to the application autoloader)
• zend-http (which uses the PluginClassLoader for loading HTTP header implementations, and should likely move to a standard plugin manager, but instead is going to be eventually deprecated in favor of Diactoros anyways)

In short: I don't know that we need to deprecate anything; it's more likely that we'll abandon it after the move to Laminas, in favor of inlining those facilities into the packages that use them currently.

[froschdesign]

@weierophinney

zend-modulemanager (which uses the ModuleAutoloader as a fallback to the application autoloader)

And there is already a pull request to drop zend-loader: zendframework/zend-modulemanager#78 😃

…it's more likely that we'll abandon it after the move to Laminas…

Okay, that's the information we need here. Thanks!

[froschdesign]

Only two minor changes are needed.

(We refuse all other adjustments here, like missing array example for ClassMapAutoloader or a separate migration section.)

[michalbundyra]

Thanks, @arueckauer!