[streams] Add SNAPSHOT-LINK argument to the bikeshed command line in README.md (#348)

The following example in README.md fails due to failure in processing SNAPSHOT-LINK on my environment:

> curl https://api.csswg.org/bikeshed/ -F file=@index.bs > index.tmp.html

Adding e.g. `-F md-Text-Macro="SNAPSHOT-LINK a"` makes it go. Can we include a fake SNAPSHOT-LINK argument like this in the instruction, or add a mode to run bikeshed without providing this?

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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/streams/issues/348