Update README from 1.0.1

[cnt000]

README seems to explain wrong configuration

I used 1.0.1 version but README is not correct.

Example:

README from master (github main page):

new CleanWebpackPlugin({
    // Simulate the removal of files
    //
    // default: false
    dry: true,
...........
})

README from ts branch:

new CleanWebpackPlugin(paths [, {options}]) -> right one for 1.0.1

example:

README from master: (https://github.com/johnagan/clean-webpack-plugin/blob/master/README.md)

    // Allow clean patterns outside of process.cwd()
    //
    // requires dry option to be explicitly set
    //
    // default: false
    dangerouslyAllowCleanPatternsOutsideProject: true,

README from ts branch: (https://github.com/johnagan/clean-webpack-plugin/blob/ts/README.md)

  // allow the plugin to clean folders outside of the webpack root.
  // Default: false - don't allow clean folder outside of the webpack root
  allowExternal: false

[chrisblossom]

The readme on master is for v2. Because v1 is no longer supported, I would recommend upgrading to v2. See also: https://github.com/johnagan/clean-webpack-plugin/issues/106

Here is a link to the readme for v1.