Update docs on web controller method return values

Closes gh-29349

Author: rstoyanchev

src/docs/asciidoc/web/webflux.adoc

@@ -1985,10 +1985,9 @@ generally supported for all return values.
   to be written (however, `text/event-stream` must be requested or declared in the mapping
   through the `produces` attribute).
 
-| Any other return value
-| If a return value is not matched to any of the above, it is, by default, treated as a view
-  name, if it is `String` or `void` (default view name selection applies), or as a model
-  attribute to be added to the model, unless it is a simple type, as determined by
+| Other return values
+| If a return value remains unresolved in any other way, it is treated as a model
+  attribute, unless it is a simple type as determined by
   {api-spring-framework}/beans/BeanUtils.html#isSimpleProperty-java.lang.Class-[BeanUtils#isSimpleProperty],
   in which case it remains unresolved.
 |===

src/docs/asciidoc/web/webmvc.adoc

@@ -2262,23 +2262,18 @@ supported for all return values.
 | Write to the response `OutputStream` asynchronously. Also supported as the body of a
   `ResponseEntity`. See <<mvc-ann-async>> and <<mvc-ann-async-http-streaming>>.
 
-| Reactive types -- Reactor, RxJava, or others through `ReactiveAdapterRegistry`
-| Alternative to `DeferredResult` with multi-value streams (for example, `Flux`, `Observable`)
-  collected to a `List`.
-
-  For streaming scenarios (for example, `text/event-stream`, `application/json+stream`),
-  `SseEmitter` and `ResponseBodyEmitter` are used instead, where `ServletOutputStream`
-  blocking I/O is performed on a Spring MVC-managed thread and back pressure is applied
-  against the completion of each write.
-
-  See <<mvc-ann-async>> and <<mvc-ann-async-reactive-types>>.
-
-| Any other return value
-| Any return value that does not match any of the earlier values in this table and that
-  is a `String` or `void` is treated as a view name (default view name selection through
-  `RequestToViewNameTranslator` applies), provided it is not a simple type, as determined by
-  {api-spring-framework}/beans/BeanUtils.html#isSimpleProperty-java.lang.Class-[BeanUtils#isSimpleProperty].
-  Values that are simple types remain unresolved.
+| Reactor and other reactive types registered via `ReactiveAdapterRegistry`
+| A single value type, e.g. `Mono`, is comparable to returning `DeferredResult`.
+  A multi-value type, e.g. `Flux`, may be treated as a stream depending on the requested
+  media type, e.g. "text/event-stream", "application/json+stream", or otherwise is
+  collected to a List and rendered as a single value. See <<mvc-ann-async>> and
+  <<mvc-ann-async-reactive-types>>.
+
+| Other return values
+| If a return value remains unresolved in any other way, it is treated as a model
+  attribute, unless it is a simple type as determined by
+  {api-spring-framework}/beans/BeanUtils.html#isSimpleProperty-java.lang.Class-[BeanUtils#isSimpleProperty],
+  in which case it remains unresolved.
 |===