Fixing emscripten docs

Author: richgel999

README.md

@@ -302,4 +302,6 @@ Download and install Emscripten:
     http://kripken.github.io/emscripten-site/docs/getting_started/downloads.html
 
 From the root directory, run:
+```c
     emcc -O3 emscripten/crn.cpp -I./inc -s EXPORTED_FUNCTIONS="['_malloc', '_free', '_crn_get_width', '_crn_get_height', '_crn_get_levels', '_crn_get_dxt_format', '_crn_get_bytes_per_block', '_crn_get_uncompressed_size', '_crn_decompress']" -s NO_EXIT_RUNTIME=1 -s NO_FILESYSTEM=1 -s ELIMINATE_DUPLICATE_FUNCTIONS=1 -s ALLOW_MEMORY_GROWTH=1 --memory-init-file 0 -o crunch.js
+```