Clarify that to_nearest may be a fraction in round().

content/docs/querying/functions.md

@@ -100,7 +100,7 @@ rate(http_requests_total{job="api-server"}[5m])
 `round(v instant-vector, to_nearest=1 scalar)` rounds the sample values of all
 elements in `v` to the nearest integer. Ties are resolved by rounding up. The
 optional `to_nearest` argument allows specifying the nearest multiple to which
-the sample values should be rounded.
+the sample values should be rounded. This multiple may also be a fraction.
 
 ## `scalar()`