create_custom_aggregation.md: Add links to PHP API Ref, Fix FQCN

Author: adriendupuis

docs/search/extensibility/create_custom_aggregation.md

@@ -18,17 +18,17 @@ code_samples/search/custom/src/Query/Aggregation/PriorityRangeAggregation.php
 The `PriorityRangeAggregation` class extends `AbstractRangeAggregation`.
 The name of the class indicates that it aggregates the results by using the Range aggregation.
 
-An aggregation must implement the `Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation` interface or inherit one of following abstract classes:
+An aggregation must implement the [`Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Core-Repository-Values-Content-Query-Aggregation.html) interface or inherit one of following abstract classes:
 
-- `Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\AbstractRangeAggregation`
-- `Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\AbstractStatsAggregation`
-- `Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\AbstractTermAggregation`
+- [`Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\AbstractRangeAggregation`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Core-Repository-Values-Content-Query-Aggregation-AbstractRangeAggregation.html)
+- [`Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\AbstractStatsAggregation`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Core-Repository-Values-Content-Query-Aggregation-AbstractStatsAggregation.html)
+- [`Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\AbstractTermAggregation`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Core-Repository-Values-Content-Query-Aggregation-AbstractTermAggregation.html)
 
 An aggregation can also implement one of the following interfaces:
 
-- `Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\FieldAggregation`, based on content field
-- `Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\LocationAggregation`, based on content location
-- `Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\RawAggregation`, based on details of the index structure
+- [`Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\FieldAggregation`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Core-Repository-Values-Content-Query-Aggregation-FieldAggregation.html), based on content field
+- [`Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\LocationAggregation`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Core-Repository-Values-Content-Query-Aggregation-LocationAggregation.html), based on content location
+- [`Ibexa\Contracts\Core\Repository\Values\Content\Query\Aggregation\RawAggregation`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Core-Repository-Values-Content-Query-Aggregation-RawAggregation.html), based on details of the index structure
 
 !!! note "Aggregation definition"
 
@@ -86,6 +86,8 @@ For the result extractor, you can use the built-in `RangeAggregationResultExtrac
     [[= include_file('code_samples/search/custom/config/aggregation_services.yaml', 19, 26) =]]
     ```
 
+    For other cases, a [`TermAggregationKeyMapper`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Solr-ResultExtractor-AggregationResultExtractor-TermAggregationKeyMapper.html) interface is also available.
+
 === "Elasticsearch"
 
     Tag the service with `ibexa.search.elasticsearch.query.location.aggregation.result.extractor`.
@@ -127,7 +129,7 @@ In a more complex use case, you must create your own visitor and extractor.
 
 === "Solr"
 
-    The aggregation visitor must implement `Ibexa\Contracts\Solr\Query\AggregationVisitor`:
+    The aggregation visitor must implement [`Ibexa\Contracts\Solr\Query\AggregationVisitor`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Solr-Query-AggregationVisitor.html):
 
     ``` php
     --8<--
@@ -137,7 +139,7 @@ In a more complex use case, you must create your own visitor and extractor.
 
 === "Elasticsearch"
 
-    The aggregation visitor must implement `Ibexa\Contracts\ElasticSearchEngine\Query\AggregationVisitor`:
+    The aggregation visitor must implement [`Ibexa\Contracts\ElasticSearchEngine\Query\AggregationVisitor`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Elasticsearch-Query-AggregationVisitor.html):
 
     ``` php
     --8<--
@@ -178,7 +180,7 @@ Finally, register the aggregation visitor as a service.
 
 === "Solr"
 
-    You must also create a result extractor, which implements  `Ibexa\Solr\ResultExtractor\AggregationResultExtractor` that transforms raw aggregation results from Solr into `AggregationResult` objects:
+    You must also create a result extractor, which implements [`Ibexa\Contracts\Solr\ResultExtractor\AggregationResultExtractor`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Solr-ResultExtractor-AggregationResultExtractor.html) that transforms raw aggregation results from Solr into `AggregationResult` objects:
 
     ``` php
     --8<--
@@ -192,7 +194,7 @@ Finally, register the aggregation visitor as a service.
 
 === "Elasticsearch"
 
-    You must also create a result extractor, which implements  `Ibexa\Contracts\ElasticSearchEngine\Query\AggregationResultExtractor` that transforms raw aggregation results from Elasticsearch into `AggregationResult` objects:
+    You must also create a result extractor, which implements  [`Ibexa\Contracts\ElasticSearchEngine\Query\AggregationResultExtractor`](../../api/php_api/php_api_reference/classes/Ibexa-Contracts-Elasticsearch-Query-AggregationResultExtractor.html) that transforms raw aggregation results from Elasticsearch into `AggregationResult` objects:
 
     ``` php
     --8<--