docs: Add notes about backstage root dir

Signed-off-by: Sergey Shevchenko <sergeyshevchdevelop@gmail.com>

docs/integrations/github/discovery.md

@@ -263,8 +263,7 @@ package, plus `@backstage/integration` for the basic credentials management:
 
 ```bash
 # From your Backstage root directory
-yarn add --cwd packages/backend @backstage/integration
-yarn add --cwd packages/backend @backstage/plugin-catalog-backend-module-github
+yarn add --cwd packages/backend @backstage/integration @backstage/plugin-catalog-backend-module-github
 ```
 
 And then add the processors to your catalog builder:

docs/permissions/getting-started.md

@@ -48,7 +48,7 @@ The permissions framework uses a new `permission-backend` plugin to accept autho
 
    ```bash
    # From your Backstage root directory
-   $ yarn add --cwd packages/backend @backstage/plugin-permission-backend
+   yarn add --cwd packages/backend @backstage/plugin-permission-backend
    ```
 
 2. Add the following to a new file, `packages/backend/src/plugins/permission.ts`. This adds the permission-backend router, and configures it with a policy which allows everything.

docs/permissions/plugin-authors/01-setup.md

@@ -41,8 +41,8 @@ The source code is available here:
 
    ```sh
    # From your Backstage root directory
-   $ yarn add --cwd packages/backend @internal/plugin-todo-list-backend @internal/plugin-todo-list-common
-   $ yarn add --cwd packages/app @internal/plugin-todo-list
+   yarn add --cwd packages/backend @internal/plugin-todo-list-backend @internal/plugin-todo-list-common
+   yarn add --cwd packages/app @internal/plugin-todo-list
    ```
 
 3. Include the backend and frontend plugin in your application: