Move libphonenumber-for-php to Validation section (#1360)

It's more suited for Validation than Numbers

README.md

 * [ByteUnits](https://github.com/gabrielelana/byte-units) - A library to parse, format and convert byte units in binary and metric systems.
 * [DecimalObject](https://github.com/php-collective/decimal-object) - A value object to handle decimals/floats easily and more precisely.
 * [IP](https://github.com/darsyn/ip) - An immutable value object for working with IPv4 and IPv6 addresses.
-* [LibPhoneNumber for PHP](https://github.com/giggsey/libphonenumber-for-php) - A PHP implementation of Google's phone number handling library.
 * [PHP Conversion](https://github.com/Crisu83/php-conversion) - Another library for converting between units of measure.
 * [PHP Units of Measure](https://github.com/triplepoint/php-units-of-measure) - A library for converting between units of measure.
 * [MathPHP](https://github.com/markrogoyski/math-php) - A math library for PHP.
 * [HTML Purifier](https://github.com/ezyang/htmlpurifier) - A standards compliant HTML filter.
 * [ISO-codes](https://github.com/ronanguilloux/IsoCodes) - A library for validating inputs according to standards from ISO, International Finance, Public Administrations, GS1, Book Industry, Phone numbers & Zipcodes for many countries.
 * [JSON Schema](https://github.com/jsonrainbow/json-schema) - A [JSON Schema](https://json-schema.org/) validation library.
+* [LibPhoneNumber for PHP](https://github.com/giggsey/libphonenumber-for-php) - A PHP implementation of Google's phone number handling library.
 * [MetaYaml](https://github.com/romaricdrigon/MetaYaml) - A schema validation library that supports YAML, JSON and XML.
 * [Respect Validation](https://github.com/Respect/Validation) - A simple validation library.
 * [Symfony HTML Sanitizer](https://github.com/symfony/html-sanitizer) - An HTML sanitizer library.