Add readme for mt_static feature.

README.md

@@ -64,3 +64,11 @@ a binary that fails with `SIGILL` on machines without AVX512.
 
 Set the `portable` feature on this crate to pass `PORTABLE=1` to RocksDB's build,
 which will create a portable binary at the cost of some performance.
+
+## Switch between /MT or /MD run time library (Only for Windows)
+
+The feature `mt_static` will request the library to be built with [/MT](https://learn.microsoft.com/en-us/cpp/build/reference/md-mt-ld-use-run-time-library?view=msvc-170)
+flag, which results in library using the static version of the run-time library.
+*This can be useful in case there's a conflict in the dependecy tree between different
+run-time versions.*
+