feat: expose interfaces from root folder (#33)

You can now import interfaces from `typescript-monads` instead of only at `typescript-monads/interfaces`

Author: patrickmichalina

src/index.ts

@@ -1,4 +1,2 @@
-export { monad } from './monads/monad'
-export { maybe } from './monads/maybe'
-export { either } from './monads/either'
-export { reader } from './monads/reader'
+export * from './monads/index'
+export * from './interfaces'

src/monads/index.ts

@@ -0,0 +1,4 @@
+export { monad } from './monad'
+export { maybe } from './maybe'
+export { either } from './either'
+export { reader } from './reader'