update docker README

.pre-commit-config.yaml

@@ -12,7 +12,7 @@ repos:
         - id: check-byte-order-marker
         - id: check-yaml
     - repo: https://github.com/crate-ci/typos
-      rev: v1.1.9
+      rev: v1.16.8
       hooks:
         - id: typos
     - repo: local

docker/README.md

@@ -72,7 +72,7 @@ container.
   processor with at least Intel AVX512DQ support.  For best performance, it is
   recommended to use processors supporting AVX512-IFMA52.
 - The docker build has been tested on,
-  - Ubuntu 20.04;
+  - Ubuntu 22.04;
   - MacOS Catalina (10.15.7).
 
 #### Running the Docker Build on MacOS
@@ -133,11 +133,11 @@ Code configuration.
 
 Once this step is successfully completed the program shall output
 ```bash
-Successfully tagged <username>/ubuntu_he_vscode:2.0.0
+Successfully tagged <username>/ubuntu_he_vscode:<hekit-version>
 
 RUN DOCKER CONTAINER ...
 Run container with
-docker run -d -p <ip addr>:<port>:8888 <username>/ubuntu_he_vscode:2.0.0
+docker run -d -p <ip addr>:<port>:8888 <username>/ubuntu_he_vscode:<hekit-version>
 Then to open vscode navigate to <ip addr>:<port> in your chosen browser
 ```
 
@@ -197,6 +197,16 @@ The toolkit will build the images in the order that they appear in the list,
 i.e. `feature-three` will be built on `feature-two` which will be built on
 `feature-one`.
 
+### Using custom base platform
+When building a docker image, `hekit` uses by default a version of Ubuntu as a
+base image that it fetches from dockerhub if it does not exist locally. This
+can be overridden as follows
+```bash
+hekit docker-build --platform <base-platform-image>
+```
+Note that this is at the user's own risk as the Dockerfiles have only been
+created with the default in mind.
+
 ## Running the Examples
 After a successful install and build of the docker container, the user should
 be greeted with a welcome message and be inside their user home directory.