Docx writer: include abstract title.

Closes #8702.

Uses localized term for abstract.

MANUAL.txt

@@ -1166,6 +1166,7 @@ header when requesting a document from a URL:
         - Author
         - Date
         - Abstract
+        - AbstractTitle
         - Bibliography
         - Heading 1
         - Heading 2

data/docx/word/styles.xml

@@ -99,6 +99,24 @@
       <w:jc w:val="center" />
     </w:pPr>
   </w:style>
+  <w:style w:type="paragraph" w:customStyle="1" w:styleId="AbstractTitle">
+    <w:name w:val="Abstract Title" />
+    <w:basedOn w:val="Normal" />
+    <w:next w:val="Abstract" />
+    <w:qFormat />
+    <w:pPr>
+      <w:keepNext />
+      <w:keepLines />
+      <w:jc w:val="center" />
+      <w:spacing w:before="300" w:after="0" />
+    </w:pPr>
+    <w:rPr>
+      <w:sz w:val="20" />
+      <w:szCs w:val="20" />
+      <w:b />
+      <w:color w:val="345A8A" />>
+    </w:rPr>
+  </w:style>
   <w:style w:type="paragraph" w:customStyle="1" w:styleId="Abstract">
     <w:name w:val="Abstract" />
     <w:basedOn w:val="Normal" />
@@ -107,7 +125,7 @@
     <w:pPr>
       <w:keepNext />
       <w:keepLines />
-      <w:spacing w:before="300" w:after="300" />
+      <w:spacing w:before="100" w:after="300" />
     </w:pPr>
     <w:rPr>
       <w:sz w:val="20" />

src/Text/Pandoc/Writers/Docx.hs

@@ -48,7 +48,7 @@ import Data.Time.Clock.POSIX
 import Data.Digest.Pure.SHA (sha1, showDigest)
 import Skylighting
 import Text.Pandoc.Class (PandocMonad, report, toLang, getMediaBag)
-import Text.Pandoc.Translations (translateTerm)
+import Text.Pandoc.Translations (Term(Abstract), translateTerm)
 import Text.Pandoc.MediaBag (lookupMedia, MediaItem(..))
 import qualified Text.Pandoc.Translations as Term
 import qualified Text.Pandoc.Class.PandocMonad as P
@@ -767,7 +767,15 @@ writeOpenXML opts (Pandoc meta blocks) = do
   date <- withParaPropM (pStyleM "Date") $ blocksToOpenXML opts [Para dat | not (null dat)]
   abstract <- if null abstract'
                  then return []
-                 else withParaPropM (pStyleM "Abstract") $ blocksToOpenXML opts abstract'
+                 else do
+                   abstractTitle <- translateTerm Abstract
+                   abstractTit <- withParaPropM (pStyleM "AbstractTitle") $
+                                   blocksToOpenXML opts
+                                     [Para [Str abstractTitle]]
+                   abstractContents <- withParaPropM (pStyleM "Abstract") $
+                                         blocksToOpenXML opts abstract'
+                   return $ abstractTit <> abstractContents
+
   let convertSpace (Str x : Space : Str y : xs) = Str (x <> " " <> y) : xs
       convertSpace (Str x : Str y : xs)         = Str (x <> y) : xs
       convertSpace xs                           = xs