Quoted .metalink, .meta4 and .torrent with '"' in man page

This is because when generating man page, if a word starting '.' is
put in the beginning of the line, it will be treated as macro.  This
sounds like docutils bug, but it will not be fixed soon, so we do this
as a workaround.

doc/manual-src/en/aria2c.rst

@@ -543,8 +543,8 @@ BitTorrent/Metalink Options
 
 .. option:: -S, --show-files[=true|false]
 
-  Print file listing of .torrent, .meta4 and .metalink file and exit.
-  In case of .torrent file, additional information
+  Print file listing of ".torrent", ".meta4" and ".metalink" file and exit.
+  In case of ".torrent" file, additional information
   (infohash, piece length, etc) is also printed.
 
 BitTorrent Specific Options
@@ -648,9 +648,9 @@ BitTorrent Specific Options
 
 .. option:: --bt-save-metadata[=true|false]
 
-  Save metadata as .torrent file. This option has effect only when
+  Save metadata as ".torrent" file. This option has effect only when
   BitTorrent Magnet URI is used.  The filename is hex encoded info
-  hash with suffix .torrent. The directory to be saved is the same
+  hash with suffix ".torrent". The directory to be saved is the same
   directory where download file is saved. If the same file already
   exists, metadata is not saved. See also :option:`--bt-metadata-only`
   option. Default: ``false``
@@ -824,8 +824,8 @@ BitTorrent Specific Options
 
 .. option:: -T, --torrent-file=<TORRENT_FILE>
 
-  The path to the .torrent file.  You are not required to use this
-  option because you can specify .torrent files without :option:`--torrent-file <-T>`.
+  The path to the ".torrent" file.  You are not required to use this
+  option because you can specify ".torrent" files without :option:`--torrent-file <-T>`.
 
 Metalink Specific Options
 ~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -847,9 +847,9 @@ Metalink Specific Options
 
 .. option:: -M, --metalink-file=<METALINK_FILE>
 
-  The file path to .meta4 and .metalink file. Reads input from stdin when ``-`` is
+  The file path to ".meta4" and ".metalink" file. Reads input from stdin when ``-`` is
   specified.  You are not required to use this option because you can
-  specify .metalink files without :option:`--metalink-file <-M>`.
+  specify ".metalink" files without :option:`--metalink-file <-M>`.
 
 .. option:: --metalink-language=<LANGUAGE>
 
@@ -1472,10 +1472,10 @@ based on the last error encountered.
   If HTTP authorization failed.
 
 25
-  If aria2 could not parse bencoded file(usually .torrent file).
+  If aria2 could not parse bencoded file(usually ".torrent" file).
 
 26
-  If .torrent file was corrupted or missing information that aria2 needed.
+  If ".torrent" file was corrupted or missing information that aria2 needed.
 
 27
   If Magnet URI was bad.
@@ -1914,10 +1914,10 @@ All code examples come from Python2.7 interpreter.
   
   
   
-  This method adds BitTorrent download by uploading .torrent file.  If
+  This method adds BitTorrent download by uploading ".torrent" file.  If
   you want to add BitTorrent Magnet URI, use :func:`aria2.addUri` method
   instead.  *torrent* is of type base64 which contains Base64-encoded
-  .torrent file.  *uris* is of type array and its element is URI which
+  ".torrent" file.  *uris* is of type array and its element is URI which
   is of type string. *uris* is used for Web-seeding.  For single file
   torrents, URI can be a complete URI pointing to the resource or if URI
   ends with /, name in torrent file is added. For multi-file torrents,
@@ -1969,8 +1969,8 @@ All code examples come from Python2.7 interpreter.
   
   
   
-  This method adds Metalink download by uploading .metalink file.
-  *metalink* is of type base64 which contains Base64-encoded .metalink
+  This method adds Metalink download by uploading ".metalink" file.
+  *metalink* is of type base64 which contains Base64-encoded ".metalink"
   file.  *options* is of type struct and its members are a pair of
   option name and value. See :ref:`rpc_options` below for more details.  If
   *position* is given as an integer starting from 0, the new download is
@@ -2207,7 +2207,7 @@ All code examples come from Python2.7 interpreter.
   ``belongsTo``
     GID of a parent download. Some downloads are a part of another
     download.  For example, if a file in Metalink has BitTorrent
-    resource, the download of .torrent is a part of that file.  If this
+    resource, the download of ".torrent" is a part of that file.  If this
     download has no parent, this key will not be included in the
     response.
   
@@ -2225,7 +2225,7 @@ All code examples come from Python2.7 interpreter.
     file. BitTorrent only. It contains following keys.
   
     ``announceList``
-      List of lists of announce URI. If .torrent file contains announce
+      List of lists of announce URI. If ".torrent" file contains announce
       and no announce-list, announce is converted to announce-list
       format.
   
@@ -3588,8 +3588,8 @@ Download only selected files using index
 
   The index is printed to the console using -S option.
 
-Download a file using a local .metalink file with user preference
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Download a file using a local metalink file with user preference
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 .. code-block:: console
 
   $ aria2c --metalink-location=jp,us --metalink-version=1.1 --metalink-language=en-US file.metalink