[deviantart] rename 'stash' to 'extra' (#302)

'stash' is already used as a name for the StashExtractor and therefore
expected to be a dictionary.

docs/configuration.rst

@@ -395,6 +395,17 @@ Description Try to follow external URLs of embedded players.
 =========== =====
 
 
+extractor.deviantart.extra
+--------------------------
+=========== =====
+Type        ``bool``
+Default     ``false``
+Description Download extra Sta.sh resources from description texts.
+
+            Note: Enabling this option also enables deviantart.metadata_.
+=========== =====
+
+
 extractor.deviantart.flat
 -------------------------
 =========== =====
@@ -487,17 +498,6 @@ Description The ``refresh_token`` value you get from linking your
 =========== =====
 
 
-extractor.deviantart.stash
---------------------------
-=========== =====
-Type        ``bool``
-Default     ``false``
-Description Extract Sta.sh resources from description texts.
-
-            Note: Enabling this option also enables deviantart.metadata_.
-=========== =====
-
-
 extractor.deviantart.wait-min
 -----------------------------
 =========== =====

docs/gallery-dl.conf

@@ -22,13 +22,13 @@
         "deviantart":
         {
             "refresh-token": null,
+            "extra": false,
             "flat": true,
             "folders": false,
             "journals": "html",
             "mature": true,
             "metadata": false,
             "original": true,
-            "stash": false,
             "wait-min": 0
         },
         "exhentai":