Doc nit-pick for Timestamp type

[timbunce]

The Elastic::Model::Types Timestamp docs say:

A Timestamp is a Num which holds floating epoch seconds, with milliseconds as decimal places.

The term 'floating' by itself and the phrase 'with milliseconds as decimal places' seem confusing to me. Assuming I understand the intent correctly I'd suggest something like:

A Timestamp is a Num which holds floating point epoch seconds, with milliseconds resolution.

[clintongormley]

ta