docs: update node compatibility (#1373)

README.md

@@ -38,7 +38,7 @@ Compatibility:
 |     v16.x.x   |   Stable    |
 |     v17.x.x   |   Stable    |
 |     v18.x.x   |   Stable    |
-|     v19.x.x   |   Pending   |
+|     v19.x.x   |   stable    |
 
 ### >= v16.0.0
 This service requires Node versions 18.14 or higher.
@@ -47,7 +47,8 @@ Compatibility:
 | Node Version  | Stablility  |
 |---------------|:-----------:|
 |     v18.14.x  |   Stable    |
-|     v19.x.x   |   Pending   |
+|     v20.x.x   |   Stable    |
+|     v21.x.x   |   Pending   |
 
 NOTE: Node LTS (`long term support`) versions start with an even number, and odd number versions are subject to a 6 month testing period with active support before they are unsupported. It is recommended to use sidecar with a stable actively maintained version of node.js.