Documentation: skipped meta-data conversion

[slycrel]

In the initial documentation, there is no mention of fields needing to be exportable to be used with the default mapper.

// metadata specifies table name and columns it must be in sync with schema.
var personMetadata = table.Metadata{
	Name:    "person",
	Columns: []string{"first_name", "last_name", "email"},
	PartKey: []string{"first_name"},
	SortKey: []string{"last_name"},
}

// personTable allows for simple CRUD operations based on personMetadata.
var personTable = table.New(personMetadata)

// Person represents a row in person table.
// Field names are converted to camel case by default, no need to add special tags.
// If you want to disable a field add `db:"-"` tag, it will not be persisted.
type Person struct {
	FirstName string
	LastName  string
	Email     []string
}

Can clarification be added that only exported fields will be mapped by the default mapper in the section above?

I lost a significant amount of time (and ended up debugging into the library) to determine that I needed to uppercase my (otherwise package internal) field names so the default mapper worked. Especially with the db:""` comment that is already there, I erroneously thought that was the way to skip fields, not also via exportablity.

[mmatczuk]

The best would be document that and also document how to work with not exported fields.
Please send a PR.

[mmatczuk]

Thanks.