DictQuickLookup:update(): strip all leading empty lines/spaces

This gets rid of sometimes huge spacing between a word and its
description taken from dictionary, and thus need for scrolling just to
read fisrs few lines of description.

frontend/apps/reader/modules/readerdictionary.lua

@@ -57,6 +57,8 @@ local function tidy_markup(results)
         end
         -- ignore all markup tags
         def = def:gsub("%b<>", "")
+        -- strip all leading empty lines/spaces
+        def = def:gsub("^%s+", "")
         result.definition = def
     end
     return results