Issue #3262860 by gaurav.kapoor: Add README file for the module and update project page description

Pikaday Calendar

****************

-- SUMMARY --

  Pikaday calendar uses the Pikaday (https://github.com/Pikaday/Pikaday) JS

  plugin to provide a Lightweight date picker.

-- INSTALLATION --

  1. Download the Pikaday JS plugin

     (https://github.com/Pikaday/Pikaday version 1.8.2 or higher is recommended)

     and extract the file under "libraries".

  2. Download and enable the module.

  3. Configure at Administer > Configuration > User interface > Pikaday Settings

     (requires administer site configuration permission)

-- INSTALLATION VIA COMPOSER --

  It is assumed you are installing Drupal through Composer using the Drupal

  Composer facade. See https://www.drupal.org/docs/develop/using-composer/using-composer-to-manage-drupal-site-dependencies#drupal-packagist

  Before you add the module using composer, you should add an installer path

  so that the Pikaday JavaScript library is installed in the correct location.

  You might have an entry similar to below in your composer.json already if

  you had used [drupal/recommended-project](https://github.com/drupal/recommended-project)

  to create your project.

```

    "extra": {

        "installer-paths": {

            "web/libraries/{$name}": ["type:drupal-library"]

        }

    }

```

  where `web/libraries/` is the path to the libraries directory relative to your

  _project_ root. Modify the entry above to add `Pikaday/Pikaday` in that array.

```

    "extra": {

        "installer-paths": {

            "web/libraries/{$name}": [

              "type:drupal-library",

              "Pikaday/Pikaday"

            ]

        }

    }

```

  Next, you need to add a custom installer-type so that composer installer

  extended plugin can pick it up. Find the `installer-types` entry in extra

  section and add `library` to it. Your entry should look something like the

  following:

```

    "extra": {

        "installer-types": [

            "library"

        ]

    }

```

  Remember, you may have other entries in there already. For this to work, you

  need to have the 'oomphinc/composer-installers-extender' installer. If you

  don't have it, or are not sure, simply run:

```

composer require oomphinc/composer-installers-extender

```

  Then, run the following composer command:

```

composer require drupal/pikaday

```

  This command will add the Pikaday Drupal module and JavaScript library to your

  project. The library will be downloaded to the `drupal-library` installer path

  you set in the first step.

-- INTEGRATING PIKADAY --

  After configuring Pikaday from the settings, you have to ensure that element

  with id #datepicker is present in your form as currently there isn't any

  provision to select the target field as well.

Pikaday Calendar

****************

TBA

        }

    },

    "require": {

        "Pikaday/Pikaday": "5.7.2"

        "Pikaday/Pikaday": "1.8.2"

    }

}

    attach: function attach(context) {

      var $context = $(context);

      var picker = new Pikaday({ field: $('#datepicker')[0] });

      // TODO: Need to make changes on this to add the pikaday calendar

      //  on input fields of type date.

      // [logs]

      // console.log($context);

    }

  };

})(jQuery, Drupal, drupalSettings);