clean up installation paths

remove unused lines, don't install empty docs dir

Author: myk002

CMakeLists.txt

@@ -1,9 +1,8 @@
 install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
         DESTINATION ${DFHACK_DATA_DESTINATION}
         FILES_MATCHING PATTERN "*.lua"
-                       PATTERN "*.rb"
                        PATTERN "*.json"
-                       PATTERN "3rdparty" EXCLUDE
+                       PATTERN "scripts/docs" EXCLUDE
                        PATTERN "scripts/test" EXCLUDE
 )