message: add link to test features
diff: * Update dependencies to [Bot Framework 4.10]
  * Update some dev dependencies like lerna, eslint, etc.
  -* NEW: Additional support for Microsoft Teams! [Read all about it!](packages/docs/core.md#ms-teams-extensions)
  +* NEW: Additional support for Microsoft Teams! [Read all about it](packages/docs/core.md#ms-teams-extensions) or [see these new methods in action](packages/testbot/features/teams_features.js)
  * Bot workers spawned from the default adapter now feature `bot.teams` which is an instance to the [TeamsInfo helper class](https://docs.microsoft.com/en-us/javascript/api/botbuilder/teamsinfo?view=botbuilder-ts-latest).
  * Botkit now includes an optional middleware [TeamsInvokeMiddleware](packages/docs/reference/core.md#TeamsInvokeMiddleware) for handling "invoke" responses from Teams including task modules.
  * Botkit now includes [bot.replyWithTaskInfo()](packages/docs/reference/core.md#replyWithTaskInfo) which can be used to respond to task module events. [Read more about Task Modules](https://docs.microsoft.com/en-us/microsoftteams/platform/task-modules-and-cards/what-are-task-modules)
  