Merge pull request #112261 from aaronp64/dictionary_set_doc

Explain `Dictionary.set()` return value in docs

Author: akien-mga

doc/classes/Dictionary.xml

@@ -508,7 +508,7 @@
 			<param index="0" name="key" type="Variant" />
 			<param index="1" name="value" type="Variant" />
 			<description>
-				Sets the value of the element at the given [param key] to the given [param value]. This is the same as using the [code][][/code] operator ([code]dict[key] = value[/code]).
+				Sets the value of the element at the given [param key] to the given [param value]. This is the same as using the [code][][/code] operator ([code]dict[key] = value[/code]). Returns [code]true[/code] if the value is set successfully. Fails and returns [code]false[/code] if the dictionary is read-only, or if [param key] and [param value] don't match the dictionary's types.
 			</description>
 		</method>
 		<method name="size" qualifiers="const">