Fixed the Doxyfile to have the right filenames for the markdown files.

Author: DavidEGrayson

Doxyfile

@@ -2,7 +2,7 @@
 PROJECT_NAME = "libusbp"
 OUTPUT_DIRECTORY = docs
 INLINE_INHERITED_MEMB = YES
-INPUT = README.md PLATFORM_NOTES.md contributing.md threads.md include
+INPUT = README.md PLATFORM_NOTES.md CONTRIBUTING.md THREADS.md include
 USE_MDFILE_AS_MAINPAGE = README.md
 RECURSIVE = YES
 SOURCE_BROWSER = YES