[docs] Add link to the MIPS 64-bit ELF object file specification

llvm-svn: 227050

Author: atanasyan

llvm/docs/CompilerWriterInfo.rst

@@ -41,6 +41,8 @@ MIPS
 
 * `MIPS Processor Architecture <http://imgtec.com/mips/mips-architectures.asp>`_
 
+* `MIPS 64-bit ELF Object File Specification <http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf>`_
+
 PowerPC
 -------