add stb_dxt.h

README.md

@@ -9,10 +9,11 @@ library | description
 **stb_vorbis.c**      | decode ogg vorbis files from memory to float/16-bit signed output
 **stb_truetype.h**    | parse, decode, and rasterize characters from truetype fonts
 **stb_image_write.h** | image writing to disk
-**stb.h**             | helper functions for C, mostly redundant in C++
-**stb_c_lexer.h**     | simplify writing parsers for C-like languages
-**stb_perlin.h**      | revised Perlin noise (3D input, 1D output)
 **stb_textedit.h**    | guts of a text editor for games etc implementing them from scratch
+**stb_dxt.h**         | Fabian "ryg" Geisen's real-time DXT compressor
+**stb_perlin.h**      | revised Perlin noise (3D input, 1D output)
+**stb_c_lexer.h**     | simplify writing parsers for C-like languages
+**stb.h**             | helper functions for C, mostly redundant in C++, basically author's personal stuff
 
 FAQ
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