Update how_it_works.md (#1293)

Hey Rector Team. I think I spotted what seems to be a typo at the end in the similar projects section specifically for hhast it says mirations rather than migrations the "g" is missing I think. But I might be wrong. Hopefully it helps. Have a great day. And thanks for this awesome tool. I am learning to use it to it's full power. Thanks again and take care.
Thanks to @samsonasik for pointing me to the right direction to find this file.

build/target-repository/docs/how_it_works.md

@@ -100,7 +100,7 @@ return static function (ContainerConfigurator $containerConfigurator): void {
 ### Similar Projects
 
 - [ClangMR](https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/41342.pdf) for C++ by Google (closed source) - almost idential workflow, developed independently though
-- [hhast](https://github.com/hhvm/hhast) - HHVM AST + format preserving + mirations
+- [hhast](https://github.com/hhvm/hhast) - HHVM AST + format preserving + migrations
 - [facebook/jscodeshift](https://github.com/facebook/jscodeshift) for Javascript
 - [silverstripe/silverstripe-upgrader](https://github.com/silverstripe/silverstripe-upgrader) for PHP CMS, Silverstripe
 - [dereuromark/upgrade](https://github.com/dereuromark/upgrade) for PHP Framework, CakePHP