Add references in bulk summary config

This will link to the BREAKTHROUGH observation section and the
LOCALIZATION keyword section in the places where they are
referenced from the bulk configuration documentation.

Author: SAKavli

docs/ert/reference/configuration/observations.rst

@@ -252,15 +252,16 @@ a well.
 The WELL keyword can contain two types of configuration: LOCALIZATION and
 BREAKTHROUGH.
 
-LOCALIZATION contains two required fields: NORTH and EAST, and optionally
-RADIUS. These localization attributes will be applied to all observations
-sharing the same well name as the WELL configuration.
-
-BREAKTHROUGH allows the user to define a BREAKTHROUGH observation for
-the given well. BREAKTHROUGH is configured like a regular
-BREAKTHROUGH_OBSERVATION - which requires the fields KEY, THRESHOLD, DATE
-and ERROR. BREAKTHROUGH will also inherit the LOCALIZATION values should
-they be defined for the well. Only one occurrence of BREAKTHROUGH can
+:ref:`LOCALIZATION <localization_keyword>` is defined like a regular
+:ref:`LOCALIZATION keyword <localization_keyword>` but will be applied to all observations
+in the csv file sharing the same well name as the WELL configuration.
+
+BREAKTHROUGH allows the user to define a
+:ref:`BREAKTHROUGH observation <breakthrough_observation>` for the given well.
+BREAKTHROUGH is configured like a regular
+:ref:`BREAKTHROUGH_OBSERVATION <breakthrough_observation>` - which requires the fields
+KEY, THRESHOLD, DATE and ERROR. BREAKTHROUGH will also inherit the LOCALIZATION values
+should they be defined for the well. Only one occurrence of BREAKTHROUGH can
 be configured per WELL.
 
 A SUMMARY configuration containing all of these elements may look like:
@@ -584,6 +585,8 @@ are correctly associated with reservoir zones.
 If a zone is specified but no ZONEMAP is provided, or if the observation location doesn't match
 the expected zone, the observation will be deactivated with a warning during the simulation.
 
+.. _localization_keyword:
+
 The LOCALIZATION keyword - Configuring observations with location
 -----------------------------------------------------------------