[DOCS] Refer to rules as custom rules (#101)

Author: dimitris-athanasiou

docs/en/stack/ml/rules.asciidoc

@@ -1,15 +1,15 @@
 [role="xpack"]
 [[ml-rules]]
-=== Machine learning rules and filters
+=== Machine learning custom rules
 ++++
-<titleabbrev>Rules and filters</titleabbrev>
+<titleabbrev>Custom Rules</titleabbrev>
 ++++
 
 By default, as described in <<ml-analyzing>>, anomaly detection is unsupervised 
 and the {ml} models have no awareness of the domain of your data. As a result, 
 {ml} jobs might identify events that are statistically significant but are 
-uninteresting when you know the larger context. Machine learning rules enable 
-you to customize anomaly detection. 
+uninteresting when you know the larger context. Machine learning custom rules
+enable you to customize anomaly detection. 
 
 _Rules_ instruct anomaly detectors to change their behavior based on 
 domain-specific knowledge that you provide. When you create a rule, you can