Schematic indicator interpretation
It is most likely that the cap should be grounded close to pin 21.

The layouter will look at the schematic while doing the layout, so its a big help if all relevant information is in the schematic.

There are various ways to indicate if a capacitor should be placed close to a specific pin on an IC.
There could be a note next to the cap, the end of the cap could be connected between pin 21 and the GND symbol, or a dotted line like your example. 

It depends on the style of the engineer drawing the schematic.