fix(docs): correct C# MatchExcept snippet (was using Match instead of MatchExcept) (#2345)

* fix(docs): correct C# MatchExcept snippet to use MatchExcept instead of Match

The C# code example in the match-except filter condition snippet was
incorrectly using Match() instead of MatchExcept(), making it identical
to the match-any example. This is misleading for developers trying to
implement the MatchExcept (NOT IN) filter condition in C#.

Fixes #1656

* Add Markdownified code snippet

---------

Co-authored-by: Abdon Pijpelink <abdon.pijpelink@qdrant.com>

qdrant-landing/content/documentation/headless/snippets/filter-condition/match-except/csharp.cs

@@ -4,6 +4,6 @@ public class Snippet
 {
 	public static async Task Run()
 	{
-		Match("color", ["black", "yellow"]);
+		MatchExcept("color", ["black", "yellow"]);
 	}
 }

qdrant-landing/content/documentation/headless/snippets/filter-condition/match-except/generated/csharp.md

@@ -1,5 +1,5 @@
 ```csharp
 using static Qdrant.Client.Grpc.Conditions;
 
-Match("color", ["black", "yellow"]);
+MatchExcept("color", ["black", "yellow"]);
 ```