enhance the documents (#389)

README.md

@@ -1,9 +1,12 @@
 # Tortoise
 
+
 <img alt="Tortoise" src="docs/images/tortoise_big.jpg" width="400px"/> 
 
 Get cute Tortoises into your Kubernetes garden and say goodbye to the days optimizing your rigid autoscalers. 
 
+_Tortoise is still in the early stage and we recommend evaluating its behaviour with your services in your development environment carefully._
+
 ## Motivation
 
 At Mercari, the responsibilities of the Platform team and the service development teams are clearly distinguished. Not all service owners possess expert knowledge of Kubernetes.
@@ -96,6 +99,13 @@ and how they can configure Tortoise so that they can let tortoises autoscale the
 
 - [Tortoise](./api/v1beta3/tortoise_types.go)
 
+## Notes
+
+Here's some notes that you may want to pay attention to before starting to use Tortoise.
+
+- Tortoise only supports Deployment at the moment. In the future, [we'll support all resources supporting scale subresources](https://github.com/mercari/tortoise/issues/129).
+- In Mercari, we've evaluated Tortoise with many Golang microservices, while there're a few services implemented in other languages using Tortoise. Any contributions would be welcome for enhance the recommendation for your language's services!
+
 ## Contribution
 
 Before implementing any feature changes as Pull Requests,

docs/user-guide.md

@@ -5,13 +5,6 @@
 This page describes a minimum knowledge that the end-users have to know, 
 and how they can configure Tortoise so that they can let tortoises autoscale their workloads.
 
-### How tortoise works
-
-Actually, Tortoise itself doesn't directly change your Pod's resource request or the number of replicas.
-
-It has HorizontalPodAutoscaler and VerticalPodAutoscaler under the hood, 
-and your tortoise just keeps updating them to be well-optimized based on your workload's historical resource usage.
-
 ### Configuration overview
 
 Tortoise is designed to be a very simple configuration: