Update links to code symbols in the glossary

The links to the code symbols in the glossary were outdated, using old
names from the logical meter.

Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>

docs/user-guide/glossary.md

@@ -188,8 +188,8 @@ microgrid are connected with each other.  Some of the ways in which the SDK uses
 the component graph are:
 
   - figure out how to calculate high level metrics like
-[`grid_power`][frequenz.sdk.timeseries.grid.Grid.power],
-[`consumer_power`][frequenz.sdk.timeseries.consumer.Consumer.power],
+[`grid().power`][frequenz.sdk.timeseries.grid.Grid.power],
+[`consumer().power`][frequenz.sdk.timeseries.consumer.Consumer.power],
 etc. for a microgrid, using the available components.
   - identify the available {{glossary("battery", "batteries")}} or
     {{glossary("EV charger", "EV chargers")}} at a site that can be controlled.