[Documentation] Update zos_fetch documentation to be clear about flat value (#2047)

* Updated zos_fetch documentation

* Updated changelogs

Author: fernandofloresg

changelogs/fragments/2047-zos_fetch-update-docs.yml

@@ -0,0 +1,3 @@
+minor_changes:
+   - zos_fetch - Updated the documentation to correctly state what the default behavior of the module is.
+     (https://github.com/ansible-collections/ibm_zos_core/pull/2047).

plugins/modules/zos_fetch.py

@@ -70,12 +70,12 @@
     type: bool
   flat:
     description:
-      - Override the default behavior of appending hostname/path/to/file to the
-        destination. If set to "true", the file or data set will be fetched to
+      - If set to "true", override the default behavior of appending hostname/path/to/file to the
+        destination, instead the file or data set will be fetched to
         the destination directory without appending remote hostname to the
         destination.
     required: false
-    default: "true"
+    default: "false"
     type: bool
   is_binary:
     description:
@@ -848,7 +848,7 @@ def run_module():
             src=dict(required=True, type="str"),
             dest=dict(required=True, type="path"),
             fail_on_missing=dict(required=False, default=True, type="bool"),
-            flat=dict(required=False, default=True, type="bool"),
+            flat=dict(required=False, default=False, type="bool"),
             is_binary=dict(required=False, default=False, type="bool"),
             use_qualifier=dict(required=False, default=False, type="bool"),
             validate_checksum=dict(required=False, default=True, type="bool"),