doc: clarify pressed find clause is accross whole cluster, not node

[wideawakening]

small nit to help avoid misunderstandings
#781 (comment)

[roosterfish]

Thanks for logging this. Its indeed something missing in the docs to make to use of the filters more transparent.
In addition we should have more concrete and practical examples about what are the various filter values, especially for find.

cc @elijahgreenstein .