docs: rewrite ObjectListFilter README section

Co-authored-by: xperiandri <2365592+xperiandri@users.noreply.github.com>

Author: Copilot

README.md

@@ -397,32 +397,10 @@ query TestQuery {
 }
 ```
 
-This filter is mapped by the middleware inside an `ObjectListFilter` definition:
+This filter is mapped by the middleware into the `ObjectListFilter` discriminated union, with cases such as `And`, `Or`, `Not`, `Equals`, `GreaterThan`, `GreaterThanOrEqual`, `LessThan`, `LessThanOrEqual`, `In`, `StartsWith`, `EndsWith`, `Contains`, `OfTypes`, and `FilterField`.
 
-```fsharp
-type FieldFilter<'Val> =
-    { FieldName : string
-      Value : 'Val }
-
-type ObjectListFilter =
-    | And of ...
-    | Or of ...
-    | Not of ...
-    | Equals of ...
-    | GreaterThan of ...
-    | GreaterThanOrEqual of ...
-    | LessThan of ...
-    | LessThanOrEqual of ...
-    | In of ...
-    | StartsWith of ...
-    | EndsWith of ...
-    | Contains of ...
-    | OfTypes of ...
-    | FilterField of ...
-```
-
-- `Equals`, `StartsWith`, `EndsWith`, and `Contains` now carry a comparer in the public DU.
-- `Equals` and `Contains` keep the non-generic `System.Collections.IComparer` because they also support non-string comparable values in the public DU.
+- `Equals`, `StartsWith`, `EndsWith`, and `Contains` now carry a comparer in the public discriminated union.
+- `Equals` and `Contains` keep the non-generic `System.Collections.IComparer` because they also support non-string comparable values in the public discriminated union.
 - When the filtered field is a string and you construct the DU cases directly, pass a `StringComparer` instance in that comparer slot: `StringComparer.Ordinal` for case-sensitive matching and `StringComparer.OrdinalIgnoreCase` for case-insensitive matching.
 - The built-in case-sensitive operators (`===`, `=@@`, `@@=`, `@=@`) still use the default comparer behavior for you.
 - `Contains` is also used for collection membership checks, so the wrapped value type inside `FieldFilter<_>` stays `System.IComparable` instead of being limited to `string`.