Fix order of operations in Tableau.__call__.__doc__

[amirebrahimi]

This is minor, but I figure it might save someone else some time.

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[amirebrahimi]

I just signed the CLA, so not sure if it will require CI to rerun.

[Strilanc]

Everyone always edits the generated docs instead of the source.

If the multiplication is in circuit order, then that's the wrong way around. I should fix that and then also separately describe it as "before/after" so it's clearer.

[amirebrahimi]

This seems to be consistent with what is specified here, though.

[Strilanc]

Fixes #819

[Strilanc]

Moved to #822 so I could edit it to get it merged. Thanks for the fix!