describe (content, type) {
        (Description.isDescription(this.description) ? this.description : (this.description = new Description()))
            .update(content, type);
    }
This function allows to describe the property for the purpose of detailed identification or documentation
generation. This function sets or updates the `description` child-property of this property.

@param {String} content The content of the description can be provided here as a string. Note that it is expected
that if the content is formatted in any other way than simple text, it should be specified in the subsequent
`type` parameter.
@param {String=} [type="text/plain"] The type of the content.

@example <caption>Add a description to an instance of Collection</caption>
 var Collection = require('postman-collection').Collection,
    mycollection;

// create a blank collection
myCollection = new Collection();
myCollection.describe('Hey! This is a cool collection.');

console.log(myCollection.description.toString()); // read the description