MediaWiki reader: fix indented tables with caption.

Closes #10390.

src/Text/Pandoc/Readers/MediaWiki.hs

@@ -209,6 +209,7 @@ table = do
                          Just w  -> fromMaybe 1.0 $ parseWidth w
                          Nothing -> 1.0
   caption <- option mempty tableCaption
+  optional newline
   optional rowsep
   hasheader <- option False $ True <$ lookAhead (skipSpaces *> char '!')
   (cellwidths,hdr) <- unzip <$> tableRow

test/command/10390.md

@@ -0,0 +1,23 @@
+```
+% pandoc -f mediawiki
+ {| class="wikitable"
+ |+ Overview of basic table markup
+ ! Key
+ |-
+ | Value
+ |}
+^D
+<table>
+<caption>Overview of basic table markup</caption>
+<thead>
+<tr>
+<th><p>Key</p></th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td><p>Value</p></td>
+</tr>
+</tbody>
+</table>
+```