Improve documentation of the metrics.exclude parameter

Change-Id: Iacf04a2eafc539fa5f8287796a196f0434c0e771

src/main/resources/Documentation/config.md

diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
index bf82194..1c2677a 100644
--- a/src/main/resources/Documentation/config.md
+++ b/src/main/resources/Documentation/config.md
@@ -15,5 +15,5 @@
 ```
 
 ```metrics.exclude```
-:   String used to exclude metrics from the report. It can be specified multiple times.
-    Parsed as regular expression. Note, ^ and $ are automatically added around the string.
+:   Regex pattern used to exclude metrics from the report. It can be specified multiple times.
+    Note that pattern matching is done on the whole metric name, not only on a part of it.