use case: unencoded plaintext license text attachment (#280)

caused by
CycloneDX/specification#382 (comment)
> [...] add an example where the encode= is not specified [...]

we have two examples of encoded text attachments in the use cases
already.

this PR makes one of them an unencoded text attachment. 
this way we have both use cases shown.

since the MIT license us not a template, but an actual text with actual
values in it,
and since it is pretty short,
I used an example with MIT license.

in contrast - the Apache license is a template - it must not be modified
and therefore it makes no practical since to have it as an attachment
...

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Signed-off-by: Jan Kowalleck <[email protected]>
Signed-off-by: Jan Kowalleck <[email protected]>

Author: jkowalleck