Update README.md

Author: findmyway

README.md

@@ -4,10 +4,7 @@
 
 This package defines two core concepts in reinforcement learning:
 
-- `AbstractEnv`.
-  - Checkout
-    [ReinforcementLearningEnvironments.jl](https://github.com/JuliaReinforcementLearning/ReinforcementLearningEnvironments.jl)
-    for versatile varieties of environments.
+- `AbstractEnv`. Checkout [ReinforcementLearningEnvironments.jl](https://github.com/JuliaReinforcementLearning/ReinforcementLearningEnvironments.jl) for versatile varieties of environments.
 - `AbstractPolicy`.
   [ReinforcementLearningCore.jl](https://github.com/JuliaReinforcementLearning/ReinforcementLearningCore.jl)
   is a good start point for how to write customized policies.