Corrected grammatical mistake in the Note section of Message Headers

This is the current statement
>SpEL evaluation context’s root object is the actual input argument, so in he case of Message<?> you can construct expression that has access to both payload and headers (e.g., spring.cloud.function.routing-expression=headers.function_name).

This is the corrected one
>SpEL evaluation context’s root object is the actual input argument, so in the case of Message<?> you can construct expression that has access to both payload and headers (e.g., spring.cloud.function.routing-expression=headers.function_name).

```diff
-so in he case...
+so in the case...
```

docs/src/main/asciidoc/spring-cloud-function.adoc

@@ -195,7 +195,7 @@ you to use Spring Expression Language (SpEL) and provide SpEL expression that sh
 into definition of a function (as described above).
 
 NOTE: SpEL evaluation context's root object is the
-actual input argument, so in he case of `Message<?>` you can construct expression that has access
+actual input argument, so in the case of `Message<?>` you can construct expression that has access
 to both `payload` and `headers` (e.g., `spring.cloud.function.routing-expression=headers.function_name`).
 
 In specific execution environments/models the adapters are responsible to translate and communicate