Write out more explicit steps for cutting a release (microsoft#388)

Author: brettcannon

CONTRIBUTING.md

@@ -112,9 +112,13 @@ time-critical as a new feature may be.
  * [tock] Begin applying any changes to the development process as
  agreed upon during the previous "tick" cycle
 * Day 7 (Monday)
- * 3rd-party dependencies frozen to give CELA time to update TPN file
+ * 3rd-party dependencies frozen
+ * Ask CELA to update the TPN file
 * Day 14 (2nd Monday)
+ * Update the TPN file as instructed by CELA
+ * Bump version number
  * Code freeze
+ * Cut a `.vsix` file for testing
  * Go through
  [issues awaiting validation](https://github.com/Microsoft/vscode-python/issues?q=label%3A%22awaiting+4-validation%22+is%3Aclosed)
  & validate they have been fixed (and not subsequently broken by
@@ -123,13 +127,14 @@ time-critical as a new feature may be.
  [documentation](https://code.visualstudio.com/docs/python/python-tutorial)
  -- including the
  [WOW](https://code.visualstudio.com/docs/languages/python) page)
- -- is updated appropriately
+ -- has [appropriate pull requests](https://github.com/microsoft/vscode-docs/pulls)
  * Update the
  [changelog](https://github.com/Microsoft/vscode-python/blob/master/CHANGELOG.md)
- * Write a post for the [team blog](https://aka.ms/pythonblog)
- * Upload the new version of
- [the extension](https://marketplace.visualstudio.com/items?itemName=ms-python.python)
  * Tag the release in git
+ * Draft a post for the [team blog](https://aka.ms/pythonblog)
+
+Assuming no last-minute issues, the release should be made public
+later that same week.
 
 ### Issue triaging