Update README.md

update document on how-to build moodle core

README.md

@@ -3,6 +3,60 @@
 
 <img width="351" alt="moodleCPDDesign1" src="https://github.com/ubc/moodle-docker/assets/86985864/acb614d9-cdb2-470c-a816-4095b96e987a">
 
+## Build Image
+
+* Step 1: for development 
+
+* HOW-TO Build Moodle CPD from MoodleCore 4.1-LTS with Github > Codespace
+
+** - (optional) fork "moodlecore-4.1LTS" branch
+
+** - From "moodlecore-4.1LTS" branch:
+    - click on the (green button) "<> CODE" 
+    - select "Codespaces" tab 
+    - click the + to launch Codespaces instance
+
+** - This will launch a default Codespaces instance with 2-core 8GB RAM, 32GB (sufficient to build this image)
+
+** - The browser navigates to the codespace instance: something like this... <some random name>gp.github.dev
+
+** - At bottom, select tab "Terminal" - this is bash shell 
+    - Edit Dockerfile or other 
+    - After completed the change (if any), then do build image
+
+** - Execute > docker-compose build
+    - After build completed, tag the image. 
+
+** - (optional) docker login -u <your hub.docker.com accout>
+
+** - Execute > docker tag <some image ID> <your hub.docker.com accout>/moodlecore:4.1.6-<unique id>
+    - example, docker tag eb73e7a5c010 hubdocker2020/moodlecore:4.1.6-eb73e7a5c010
+
+** - Execute > docker push <your hub.docker.com accout>/moodlecore:4.1.6-<unique id>
+    - example, docker push hubdocker2020/moodlecore:4.1.6-eb73e7a5c010
+
+** - DONE with MoodleCore 4.1 LTS, on your hub.docker.com account. 
+
+
+
+* Step 2: for deployment to STAGING or PROD
+
+* After completion of Option 1 above:
+
+** - commit the change back to main repo branch "moodlecore-4.1LTS"
+
+** - this action will trigger auto build of image and it should be ready for next step
+
+** - DONE with MoodleCore 4.1 LTS, but on LTHub: https://hub.docker.com/u/lthub
+
+
+
+* Step 3: for building Moodle CPD with images from Step 1 or Step 2 above:
+
+** Link here: https://github.com/ubc/moodle-docker/tree/moodlecpd-4.1LTS
+
+-----------------------
+
 * Source: https://moodledev.io/general/releases/4.1
 
 ## Known Issues