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

Patch by Miloš Stojanović

Differential Revision: https://reviews.llvm.org/D69377

Author: atanasyan

llvm/docs/CompilerWriterInfo.rst

@@ -50,7 +50,7 @@ MIPS
 
 * `MIPS Processor Architecture <https://www.mips.com/products/>`_
 
-* `MIPS 64-bit ELF Object File Specification <http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf>`_
+* `MIPS 64-bit ELF Object File Specification <https://www.linux-mips.org/pub/linux/mips/doc/ABI/elf64-2.4.pdf>`_
 
 PowerPC
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