Update Dotnet Matrix - Add Links after span creation (#4291)

Author: cijothomas

spec-compliance-matrix.md

@@ -68,7 +68,7 @@ formats is required. Implementing more than one format is optional.
 | Unicode support for keys and string values                                                       |          | +   | +    | +   | +      | +    | +      | +   | +    | +   | +    | +     |
 | [Span linking](specification/trace/api.md#specifying-links)                                      | Optional | Go  | Java | JS  | Python | Ruby | Erlang | PHP | Rust | C++ | .NET | Swift |
 | Links can be recorded on span creation                                                           |          | +   | +    |     | +      | +    | +      | +   | +    | +   | +    |       |
-| Links can be recorded after span creation                                                        |          | +   |      |     | +      |      |        |     |      | +   |      |       |
+| Links can be recorded after span creation                                                        |          | +   |      |     | +      |      |        |     |      | +   | +    |       |
 | Links order is preserved                                                                         |          | +   | +    |     | +      | +    | +      | +   | +    | +   | +    |       |
 | [Span events](specification/trace/api.md#add-events)                                             | Optional | Go  | Java | JS  | Python | Ruby | Erlang | PHP | Rust | C++ | .NET | Swift |
 | AddEvent                                                                                         |          | +   | +    | +   | +      | +    | +      | +   | +    | +   | +    | +     |