docs: move regex docs

README.md

@@ -80,6 +80,10 @@ Restrict to a minimum length
 ```directives: [constraints: [format: :uuid]]```
 Ensure value is in a particular format
 
+#### pattern
+```directives: [constraints: [pattern: "^[A-Z][0-9a-z]*$"]]```
+Ensure value follows a specific Regex pattern
+
 Supported formats:
 - `:uuid` - uses :elixir_uuid to validate the value
 - `:email` - uses a regex to validate the value
@@ -103,9 +107,3 @@ Restrict to a minimum number of items
 #### max
 ```directives: [constraints: [max_items: 5]]```
 Restrict to a maximum number of items
-
-### Regex
-
-#### pattern
-```directives: [constraints: [pattern: "^[A-Z][0-9a-z]*$"]]```
-Ensure value follows a specific Regex pattern