org-export and back-ends: Fix some docstrings

contrib/lisp/org-e-ascii.el

@@ -1736,10 +1736,9 @@ EXT-PLIST, when provided, is a property list with external
 parameters overriding Org default settings, but still inferior to
 file-local settings.
 
-When optional argument PUB-DIR is set, use it as the publishing
-directory.
-
-Return output file's name."
+Export is done in a buffer named \"*Org E-ASCII Export*\", which
+will be displayed when `org-export-show-temporary-export-buffer'
+is non-nil."
   (interactive)
   (let ((outbuf (org-export-to-buffer
 		 'e-ascii "*Org E-ASCII Export*"

contrib/lisp/org-export.el

@@ -4288,7 +4288,7 @@ entry.")
   "Translate string S according to language specification.
 
 ENCODING is a symbol among `:ascii', `:html', `:latex', `:latin1'
-and `:utf8'.  INFO is a plist used as a communication channel.
+and `:utf-8'.  INFO is a plist used as a communication channel.
 
 Translation depends on `:language' property.  Return the
 translated string.  If no translation is found return S."

contrib/lisp/org-md.el

@@ -373,10 +373,9 @@ first.
 When optional argument VISIBLE-ONLY is non-nil, don't export
 contents of hidden elements.
 
-When optional argument PUB-DIR is set, use it as the publishing
-directory.
-
-Return output file's name."
+Export is done in a buffer named \"*Org MD Export*\", which will
+be displayed when `org-export-show-temporary-export-buffer' is
+non-nil."
   (interactive)
   (let ((outbuf (org-export-to-buffer
 		 'md "*Org MD Export*" subtreep visible-only)))