[doc] add sanitizers documentation in developer-notes.md

Coming straight from btc@6feb46c3721605f6ae54d7e635a06f82cd7c1449

Author: furszy

doc/developer-notes.md

@@ -261,6 +261,48 @@ make cov
 # A coverage report will now be accessible at `./test_pivx.coverage/index.html`.
 ```
 
+**Sanitizers**
+Bitcoin can be compiled with various "sanitizers" enabled, which add
+instrumentation for issues regarding things like memory safety, thread race
+conditions, or undefined behavior. This is controlled with the
+`--with-sanitizers` configure flag, which should be a comma separated list of
+sanitizers to enable. The sanitizer list should correspond to supported
+`-fsanitize=` options in your compiler. These sanitizers have runtime overhead,
+so they are most useful when testing changes or producing debugging builds.
+Some examples:
+ ```bash
+ # Enable both the address sanitizer and the undefined behavior sanitizer
+ ./configure --with-sanitizers=address,undefined
+ # Enable the thread sanitizer
+ ./configure --with-sanitizers=thread
+ ```
+If you are compiling with GCC you will typically need to install corresponding
+"san" libraries to actually compile with these flags, e.g. libasan for the
+address sanitizer, libtsan for the thread sanitizer, and libubsan for the
+undefined sanitizer. If you are missing required libraries, the configure script
+will fail with a linker error when testing the sanitizer flags.
+The test suite should pass cleanly with the `thread` and `undefined` sanitizers,
+but there are a number of known problems when using the `address` sanitizer. The
+address sanitizer is known to fail in
+[sha256_sse4::Transform](/src/crypto/sha256_sse4.cpp) which makes it unusable
+unless you also use `--disable-asm` when running configure. We would like to fix
+sanitizer issues, so please send pull requests if you can fix any errors found
+by the address sanitizer (or any other sanitizer).
+Not all sanitizer options can be enabled at the same time, e.g. trying to build
+with `--with-sanitizers=address,thread` will fail in the configure script as
+these sanitizers are mutually incompatible. Refer to your compiler manual to
+learn more about these options and which sanitizers are supported by your
+compiler.
+Additional resources:
+* [AddressSanitizer](https://clang.llvm.org/docs/AddressSanitizer.html)
+* [LeakSanitizer](https://clang.llvm.org/docs/LeakSanitizer.html)
+* [MemorySanitizer](https://clang.llvm.org/docs/MemorySanitizer.html)
+* [ThreadSanitizer](https://clang.llvm.org/docs/ThreadSanitizer.html)
+* [UndefinedBehaviorSanitizer](https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html)
+* [GCC Instrumentation Options](https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html)
+* [Google Sanitizers Wiki](https://github.com/google/sanitizers/wiki)
+* [Issue #12691: Enable -fsanitize flags in Travis](https://github.com/bitcoin/bitcoin/issues/12691)
+
 Locking/mutex usage notes
 -------------------------