docs(slack): add required bot scopes to readme (#40)

* Update README.md

Fix package path.
Add information about Slack scopes.

* fix linter issue

---------

Co-authored-by: Zach Hammer <zhammer@seatgeek.com>

plugins/slack-catalog-backend/README.md

@@ -10,7 +10,7 @@ Install the `@seatgeek/backstage-plugin-slack-catalog-backend` package in your b
 
 ```shell
 # From your Backstage root directory
-yarn add --cwd packages/app @seatgeek/backstage-plugin-slack-catalog-backend
+yarn add --cwd packages/backend @seatgeek/backstage-plugin-slack-catalog-backend
 ```
 
 Add the following config to your `app-config.yaml`:
@@ -20,6 +20,8 @@ slackCatalog:
   token: ${SLACK_API_TOKEN_CATALOG}
 ```
 
+More information about Slack scopes [requirements](https://api.slack.com/scopes/users:read.email).
+
 ## Processors
 
 ### `SlackUserProcessor`