Update outdated examples in README.md

[mxr576]

The README.md file contains some outdated/incomplete examples about how composer patches should be used.

• (Minor) Very old Drupal dependency is referenced.
• Examples should either depend on drupal/core or install Drupal with drupal-composer/drupal-project. Installing Drupal with drupal/drupal is the worst possible way. See: https://www.drupal.org/docs/develop/using-composer/using-composer-to-manage-drupal-site-dependencies#note-warning
• Examples should patch drupal/core instead of drupal/drupal.
• At least one example should describe patchLevel and why drupal/core patch level should be set to -p2. See: Bump minimum required composer-patches version to support default patch level drupal-composer/drupal-project#410

[frederickjh]

@mxr576 I would suggest submitting a pull request for these making each task a separate commit.

[cweagans]

I've made a note to capture these things when updating docs for 2.x.

[xurizaemon]

In #407 there's mention that patching from dependencies is no longer supported. That will need to be reflected in the README update.

Edit: oops, old closed issue!