[docs] Fix Scudo documentation error

[cryptoad]

Summary

No Pygments lexer found for "none".

[flowerhack]

LGTM

docs/ScudoHardenedAllocator.rst

 ``whole-archive`` linker flag (or equivalent), depending on your linker.
 Additional flags might also be necessary.
 
 Your linked binary should now make use of the Scudo allocation and deallocation
 functions.
 
 You may also build Scudo like this: 
 
-.. code:: none
+.. code::
 
   cd $LLVM/projects/compiler-rt/lib
   clang++ -fPIC -std=c++11 -msse4.2 -O2 -I. scudo/*.cpp \
     $(\ls sanitizer_common/*.{cc,S} | grep -v "sanitizer_termination\|sanitizer_common_nolibc") \
     -shared -o scudo-allocator.so -pthread
 
 and then use it with existing binaries as follows:
 
-.. code:: none
+.. code::
 
   LD_PRELOAD=`pwd`/scudo-allocator.so ./a.out
 
 Options
 -------
 Several aspects of the allocator can be configured through the following ways:
 
 - by defining a ``__scudo_default_options`` function in one's program that
   returns the options string to be parsed. Said function must have the following
   prototype: ``extern "C" const char* __scudo_default_options()``.
 
 - through the environment variable SCUDO_OPTIONS, containing the options string
   to be parsed. Options defined this way will override any definition made
   through ``__scudo_default_options``;
 
 The options string follows a syntax similar to ASan, where distinct options
 can be assigned in the same string, separated by colons.
 
 For example, using the environment variable:
 
-.. code:: none
+.. code::
 
   SCUDO_OPTIONS="DeleteSizeMismatch=1:QuarantineSizeKb=64" ./a.out
 
 Or using the function:
 
 .. code:: cpp
 
   extern "C" const char *__scudo_default_options() {