Create block: Add more options to control the plugin created

[gziolo]

Description

Moved from gziolo/create-wordpress-block#1.

There was this question from @bph:

If I wanted to use it for a single block plugin, and I see a great use case for it, but it would need boilerplate pluginname.php. I created the file added the header information and move the index.php information to that file. That was easy, so easy, that it might go into the script?

It was already addressed but there are two action items left:

• Add readme.txt file to both existing templates (ES5 and ESNext)
• Make it possible to override default values with prompts for fields like author, license or version:
  

  gutenberg/packages/create-block/lib/templates.js

  Lines 24 to 26 in 07e8b84

  	author,
  	license,
  	version,

More details

Comment from @bph:

For the plugin directory, we also need the readme.txt file that holds the information displayed in the WP directory for "Tags" "Installation" "Description" "Screenshot" "Version" etc..

Here are two examples of readme text from my favorite plugins.

@JJJ Post Type Switcher
@ocean90 Public Post Preview

Comment from @ntwb:

See also:

"Readme files: To make your entry in the plugin browser most useful, each plugin should have a readme file named readme.txt that adheres to the WordPress plugin readme file standard. You can put your readme file through the readme validator to check it. "
• https://wordpress.org/plugins/readme.txt
• https://wordpress.org/plugins/developers/readme-validator/

[pereirinha]

@gziolo I opened a PR to address this issue. However, I'm having trouble to test the proposed code change. So far, all attempts have failed.

Thank you.