Please support <small> in HTML input and translate it to [.small] in AsciiDoc output.

Sample input:

This <small>MUST NOT</small> be done.

Sample output:

This [.small]#MUST NOT# be done.

Extra information:

• AsciiDoc Reference: “Asciidoctor User Manual”, section: “Custom Styling With Attributes”
• HTML5 reference: small tag (W3C HTML Reference)