doc: Add workspace initialization into existing NCS workspace

Adding instructions for initializing workspace into
an existing NCS workspace.

Signed-off-by: Tommi Rantanen <tommi.rantanen@nordicsemi.no>

Author: trantanen

README.md

@@ -56,9 +56,13 @@ Follow the official
 
 ### Initialization
 
+This section represents alternative approaches for initializing the workspace.
+
+#### Initialize workspace from scratch
+
 The first step is to initialize the workspace folder (``my-workspace``) where
-the ``ncs-example-application`` and all nRF Connect SDK modules will be cloned. Run the following
-command:
+the ``ncs-example-application`` and all nRF Connect SDK modules will be cloned.
+Run the following commands:
 
 ```shell
 # initialize my-workspace for the ncs-example-application (main branch)
@@ -68,6 +72,20 @@ cd my-workspace
 west update
 ```
 
+#### Add application into existing nRF Connect SDK workspace
+
+Assume you have an existing nRF Connect SDK workspace in the :file:`my-workspace` folder. Run the following commands:
+
+```shell
+# Navigate to the workspace folder
+cd my-workspace
+# Clone application repository
+git clone https://github.com/nrfconnect/ncs-example-application
+# Set manifest path to the application directory
+west config manifest.path ncs-example-application
+west update
+```
+
 ### Building and running
 
 To build the application, run the following command: