Port TSAN wiki to clang docs

https://github.com/google/sanitizers/wiki/ has many useful docs on TSAN. The most popular google search result for TSAN_OPTIONS is https://github.com/google/sanitizers/wiki/ThreadSanitizerFlags (although this page specifically has not been updated since 2015; is it up to date?).

Should we port these over into clang's docs (`clang/docs/ThreadSanitizer.rst` or another page in this directory)? Note: TSAN is not clang specific since it's supported in GCC, and the same wiki also has great docs on ASAN which is also supported by GCC.