fix typo

Author: wzrdtales

README.md

@@ -12,6 +12,6 @@ using your regular `tsconfig.json`
 Do however note that this has no effect on generating new migrations.
 Using `db-migrate create FooMigrations.ts` will not create a TypeScript migration file.
 
-## Immplementation Detail
+## Implementation Detail
 
 The plugin hooks into the functionality of `db-migrate` itself. In this case it hooks into `migrator:migration:hook:require`, which in this case requires another transpiler (TypeScript) and registers also a new file extension (.ts). Make sure to name your migrations accordingly (ending with .ts).