Update the contributing guide to cover our weekly sprints (#13026)

CONTRIBUTING.md

@@ -253,17 +253,14 @@ than the next sprint from when it was submitted (see
 
 ### Release cycle
 
-Planning is done as two week sprints. We start a sprint every other Wednesday.
-You can look at the newest
-[milestone](https://github.com/Microsoft/vscode-python/milestones) to see when
-the current sprint ends. All
-[P0](https://github.com/Microsoft/vscode-python/labels/P0) issues are expected
+Planning is done as one week sprints. We start a sprint every Thursday.
+All [P0](https://github.com/Microsoft/vscode-python/labels/P0) issues are expected
 to be fixed in the current sprint, else the next release will be blocked.
 [P1](https://github.com/Microsoft/vscode-python/labels/P1) issues are a
 top-priority and we try to close before the next release. All other issues are
 considered best-effort for that sprint.
 
-The extension aims to do a new release every four weeks (two sprints). A
+The extension aims to do a new release once a month. A
 [release plan](https://github.com/Microsoft/vscode-python/labels/release%20plan)
 is created for each release to help track anything that requires a
 person to do (long-term this project aims to automate as much of the