[#234] [Docs] Fix codox source-uri to play better with cljx files (@nberger)

cljx files are taken from the compiled file in target/classes for codox, but
the 'view source' links to those files should point to the original cljx file
in the src dir

project.clj

@@ -81,7 +81,9 @@
 
   :codox
   {:language :clojure
-   :source-uri "https://github.com/ptaoussanis/timbre/blob/master/{filepath}#L{line}"}
+   :source-uri
+   {#"target/classes" "https://github.com/ptaoussanis/timbre/blob/v{version}/src/{classpath}x#L{line}"
+    #".*"             "https://github.com/ptaoussanis/timbre/blob/v{version}/{filepath}#L{line}"}}
 
   :aliases
   {"test-all"   ["do" "clean," "cljx" "once,"