Add faq for non-main thread init crash (#1384)

README.md

@@ -167,6 +167,14 @@ increasing amount of V8's API in Rust.
 
 Use `export GN_ARGS="no_inline_line_tables=false"` during build.
 
+**My program crashes when initializing on non-main thread**
+
+Initializing V8 on a non-main thread with the CPUs PKU feature enabled might
+lead to crashes. You can work around this problem by using
+`v8::new_unprotected_default_platform`.
+
+See https://github.com/denoland/rusty_v8/issues/1381
+
 ## For maintainers
 
 **Cut a release**