Update actions.md: correct UpdateMSU options

[iamacarpet]

The example for UpdateMSU in the docs is misleading.

The option need to be an array of updates, each itself an array of arguments.

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[TsekNet]

Nit: Can you move each list argument to it's own line to make it easier for humans to read?

[TsekNet]

ping @iamacarpet

[iamacarpet]

Sorry @TsekNet , I'll get this sorted.

[iamacarpet]

There we go @TsekNet ,

I hope you don't mind me also documenting the argument list, as I found myself having to dive into the code again to confirm the hash format (until I realised I could guess it from the hash length, but that isn't the point) :).