Clarify purpose again

README.md

@@ -1,4 +1,4 @@
-# Docker image for building nRF Connect SDK applications
+# Dockerfile example for building nRF Connect SDK applications
 
 ![Publish Docker](https://github.com/NordicPlayground/nrf-docker/workflows/Publish%20Docker/badge.svg?branch=saga)
 (_the [Docker image](https://hub.docker.com/r/nordicplayground/nrfconnect-sdk) is build against [nRF Connect SDK](https://github.com/nrfconnect/sdk-nrf) `main`,`v2.4-branch`,`v2.3-branch`,`v2.2-branch`,`v2.1-branch`, and `v2.0-branch` every night._)
@@ -7,13 +7,13 @@
 
 This project defines a Docker image that contains all dependencies to run `west` commands with the nRF Connect SDK. Bind mount the project folder you'd like to build, and the output will end up in the same folder (nested in build/zephyr subdir of the app).
 
-The aim is to provide a Docker image that can compile application and samples in a [nRF Connect SDK](https://github.com/nrfconnect/sdk-nrf) release branch, not to exactly replicate the software configuration used when the release was made.
+The aim is to provide an example for a Docker image that can compile application and samples in a [nRF Connect SDK](https://github.com/nrfconnect/sdk-nrf) release branch, not to exactly replicate the software configuration used when the release was made.
 
 More specificially, the purpose of this project is _not_ to provide stable images, but replicate what users are facing when they start developing with nRF Connect SDK (which itself does not provide a reproducible build environment). This is mitigated by the [Toolchain Manager](https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/installation/assistant.html#install-toolchain-manager), which is available for command line usage.
 
 However, provisioning an environment with the toolchain and an updated west environment still takes considerable time (around 10 minutes). Especially with matrix builds this will quickly add up. Therefore this project shows how to dockerize a ready-to-use `west build` command.
 
-If you want stable Docker images, use the [Dockerfile](./Dockerfile) in this repository as an example to build your own Docker image.
+If you want stable Docker images or have custom needs, use the [Dockerfile](./Dockerfile) in this repository as an example to build your own Docker image.
 
 For Matter applications, check out [nrfconnect-chip-docker](https://github.com/NordicPlayground/nrfconnect-chip-docker/).