Fix incomplete wording about data validation

[Markus-Elfring]

Version

4.3.5

Context

The API documentation provides the following information.

• vertx-json-schema/src/main/java/io/vertx/json/schema/Validator.java

  Line 37 in eba3d06

  * Validate a given input against the initial schema

• vertx-json-schema/src/main/java/io/vertx/json/schema/Validator.java

  Line 19 in eba3d06

  * A validator, validates some input object using a well known schema.

💭 Thus I find an other wording more appropriate than “To validate a schema:” in the user documentation.