Persist the deprecation of fields

[RichardInnocent]

Fixes #9

[a-h]

Thanks for that.

[joerdav]

The go doc deprecation works slightly different from this, by paragraph it means the beginning of a block of text rather than a line:

type s struct {
	// MyNotDeprecatedField is not deprecated though it may seem it
	// Deprecated: don't use this field
	MyNotDeprecatedField string
	
	// Deprecated: don't use this field
	// MyDeprecatedField is deprecated
	MyDeprecatedField string
	
	// AnotherDeprecatedField is deprecated
	//
	// Deprecated: don't use this field
	AnotherDeprecatedField string
}

[RichardInnocent]

@joerdav Maybe, the documentation seems somewhat ambiguous. I wondered this myself and tested it in Goland before raising this PR which seems to think the line in the middle isn't necessary.

[joerdav]

Interesting, I think maybe goland detects it in this case. But thing such as static check won't pick it up.

But maybe this solution is fine anyway, probably doesn't matter!