Allow for mapping descriptions

Change-Id: I6e0124c36bb89226524c41d19cf69d04d8e19a79
diff --git a/config/config.go b/config/config.go
index ff0db31..dd1e3e9 100644
--- a/config/config.go
+++ b/config/config.go
@@ -21,12 +21,13 @@
 
 // MappingList represents a list of mapping rules with metadata
 type MappingList struct {
-	ID       string        `yaml:"id"`
-	FoundryA string        `yaml:"foundryA,omitempty"`
-	LayerA   string        `yaml:"layerA,omitempty"`
-	FoundryB string        `yaml:"foundryB,omitempty"`
-	LayerB   string        `yaml:"layerB,omitempty"`
-	Mappings []MappingRule `yaml:"mappings"`
+	ID          string        `yaml:"id"`
+	Description string        `yaml:"desc,omitempty"`
+	FoundryA    string        `yaml:"foundryA,omitempty"`
+	LayerA      string        `yaml:"layerA,omitempty"`
+	FoundryB    string        `yaml:"foundryB,omitempty"`
+	LayerB      string        `yaml:"layerB,omitempty"`
+	Mappings    []MappingRule `yaml:"mappings"`
 }
 
 // MappingConfig represents the root configuration containing multiple mapping lists