[TySan] Add documentation analagous to address sanitizer & thread sanitizer documentation

[seanm]

Unless I'm just missing it, TySan (type sanitizer) doesn't have any doc analogous to these two:

• https://clang.llvm.org/docs/AddressSanitizer.html
• https://clang.llvm.org/docs/ThreadSanitizer.html

Those are both great write ups, and users like me would benefit from something similar for TySan.

Some ideas of things to cover:

• ASan & TSan cannot be used together. Similar limitations with TySan?
• Do suppressions work the same as with other sanitzers?
• is there a __has_feature to detect TySan?
• is there a __attribute__((no_sanitize("type")))?
• can TySan be configured to trap instead of just log?
• TySan error messages are often of the form:

==4848==ERROR: TypeSanitizer: type-aliasing-violation on address 0x00016cfc71f0 (pc 0x000102e3b690 bp 0x00016cfc6ea0 sp 0x00016cfc6620 tid 24776816) READ of size 8 at 0x00016cfc71f0 with type p1 omnipotent char (in <anonymous type> at offset 8) accesses an existing object of type p1 omnipotent char (in <anonymous type> at offset 8) #0 0x000102e3b68c in free_opts_mem test.c:20

• The terms "omnipotent char", "type p1", etc. should be documented & explained

[seanm]

I think the new docs cover just about all of this, thanks!