Make requested changes to PR

Author: TauOmicronMu

message-index/messages/GHC-04584/index.md

@@ -1,10 +1,12 @@
 ---
 title: Expression syntax in pattern
-summary: There has been an attempt to pattern match on Expression syntax. 
+summary: There has been an attempt to pattern match on expression syntax. 
 severity: error
 introduced: 9.6.1
 ---
 
+Pattern matching allows constructors and literals to be used to take apart values, exposing their contents. The syntax of patterns is very similar to that of the expressions that create values, but many constructs that are allowed in expression contexts are not meaningful patterns. 
+
 ## Example Text
 
 ```   

message-index/messages/GHC-04584/matchingdots/index.md

@@ -2,7 +2,7 @@
 title: Using .. in pattern 
 ---
 
-When pattern matching, Expressions are not allowed as patterns to be matched against. Instead, consider matching on a list, and using a conditional. 
+When pattern matching, expressions are not allowed as patterns to be matched against. Instead, consider matching on a list, and using a conditional. 
 
 
 # Error Message