CreDocument: add "md" (Markdown) to supported filetypes

Fixes #2632.

frontend/document/credocument.lua

@@ -463,25 +463,27 @@ function CreDocument:findText(pattern, origin, reverse, caseInsensitive)
 end
 
 function CreDocument:register(registry)
-    registry:addProvider("txt", "text/plain", self)
-    registry:addProvider("log", "text/plain", self)
-    registry:addProvider("txt.zip", "application/zip", self)
-    registry:addProvider("log.zip", "application/zip", self)
+    registry:addProvider("azw", "application/azw", self)
     registry:addProvider("epub", "application/epub", self)
+    registry:addProvider("chm", "application/chm", self)
+    registry:addProvider("doc", "application/doc", self)
     registry:addProvider("fb2", "application/fb2", self)
     registry:addProvider("fb2.zip", "application/zip", self)
     registry:addProvider("html", "application/html", self)
     registry:addProvider("html.zip", "application/zip", self)
     registry:addProvider("htm", "application/htm", self)
     registry:addProvider("htm.zip", "application/zip", self)
-    registry:addProvider("rtf", "application/rtf", self)
+    registry:addProvider("log", "text/plain", self)
+    registry:addProvider("log.zip", "application/zip", self)
+    registry:addProvider("md", "text/plain", self)
+    registry:addProvider("md.zip", "application/zip", self)
     registry:addProvider("mobi", "application/mobi", self)
-    registry:addProvider("prc", "application/prc", self)
-    registry:addProvider("azw", "application/azw", self)
-    registry:addProvider("chm", "application/chm", self)
     registry:addProvider("pdb", "application/pdb", self)
-    registry:addProvider("doc", "application/doc", self)
+    registry:addProvider("prc", "application/prc", self)
     registry:addProvider("tcr", "application/tcr", self)
+    registry:addProvider("txt", "text/plain", self)
+    registry:addProvider("txt.zip", "application/zip", self)
+    registry:addProvider("rtf", "application/rtf", self)
 end
 
 return CreDocument