Clarify whether base64 encoding of license content is really optional

The specs (incl 1.4) are unclear about whether it is mandatory or optional to use base64 encoding for license text's "content".

The fact the doc for "encoding" states it "must be one of"... "base64" makes me think it's mandatory to use base64, but the fact it also says "Specifies the **optional** encoding" makes me think maybe it's optional (e.g. if I don't specify an encoding parameter maybe it's treated as normal unencoded text). I looked at the examples but there is none that have content without encoding.

Can you clarify, and in the next spec put something into the doc of the "content" field to make clear whether plain unencoded text is permitted? And maybe something in the examples to demonstrate unencoded text.

(btw I'm very much hoping that use of base64 is not mandatory for this field - many licenses make it legally necessary to include the full license text and the SBOM is a very natural place to put that... but I doubt a law court would accept a base64 encoding of the text as meeting that requirement)