fixed typo

Author: nebulark

src/doc/unstable-book/src/compiler-flags/patchable-function-entry.md

@@ -18,7 +18,7 @@ nop
 ```
 
 This flag is used for hotpatching, especially in the Linux kernel. The flag
-arguments are modeled after hte `-fpatchable-function-entry` flag as defined
+arguments are modeled after the `-fpatchable-function-entry` flag as defined
 for both [Clang](https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fpatchable-function-entry)
 and [gcc](https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#index-fpatchable-function-entry)
 and is intended to provide the same effect.