update README

Author: roycaihw

README.md

@@ -82,15 +82,16 @@ supported versions of Kubernetes clusters.
 
 #### Compatibility matrix
 
-|                    | Kubernetes 1.9 | Kubernetes 1.10 | Kubernetes 1.11 | Kubernetes 1.12 | Kubernetes 1.13 | Kubernetes 1.14 |
-|--------------------|----------------|-----------------|-----------------|-----------------|-----------------|-----------------|
-| client-python 5.0  |✓               |-                |-                |-                |-                |-                |
-| client-python 6.0  |+               |✓                |-                |-                |-                |-                |
-| client-python 7.0  |+               |+                |✓                |-                |-                |-                |
-| client-python 8.0  |+               |+                |+                |✓                |-                |-                |
-| client-python 9.0  |+               |+                |+                |+                |✓                |-                |
-| client-python 10.0 |+               |+                |+                |+                |+                |✓                |
-| client-python HEAD |+               |+                |+                |+                |+                |✓                |
+|                    | Kubernetes 1.9 | Kubernetes 1.10 | Kubernetes 1.11 | Kubernetes 1.12 | Kubernetes 1.13 | Kubernetes 1.14 | Kubernetes 1.15 |
+|--------------------|----------------|-----------------|-----------------|-----------------|-----------------|-----------------|-----------------|
+| client-python 5.0  |✓               |-                |-                |-                |-                |-                |-                |
+| client-python 6.0  |+               |✓                |-                |-                |-                |-                |-                |
+| client-python 7.0  |+               |+                |✓                |-                |-                |-                |-                |
+| client-python 8.0  |+               |+                |+                |✓                |-                |-                |-                |
+| client-python 9.0  |+               |+                |+                |+                |✓                |-                |-                |
+| client-python 10.0 |+               |+                |+                |+                |+                |✓                |-                |
+| client-python 11.0 |+               |+                |+                |+                |+                |+                |✓                |
+| client-python HEAD |+               |+                |+                |+                |+                |+                |✓                |
 
 Key:
 
@@ -118,6 +119,7 @@ between client-python versions.
 | 9.0             | Kubernetes main repo, 1.13 branch    | ✓                             |
 | 10.0 Alpha/Beta | Kubernetes main repo, 1.14 branch    | ✗                             |
 | 10.0            | Kubernetes main repo, 1.14 branch    | ✓                             |
+| 11.0 Alpha/Beta | Kubernetes main repo, 1.15 branch    | ✓                             |
 
 Key: