message: Fix a README typo
diff: [HermitCore]( http://www.hermitcore.org ) is a [unikernel](http://unikernel.org) targeting a scalable and predictable runtime for high-performance and cloud computing.
  Unikernel means, you bundle your application directly with the kernel library, so that it can run without any installed operating system.
  -This reduces overhead, therfore, interesting applications include virtual machines and high-performance computing.
  +This reduces overhead, therefore, interesting applications include virtual machines and high-performance computing.
  The RustyHermit can run Rust applications, as well as C/C++/Go/Fortran applications.
  A tutorial on how to use these programming languages on top of RustyHermit is published at [https://github.com/hermitcore/hermit-playground](https://github.com/hermitcore/hermit-playground).
  