Update sharing.md - adding some preliminary thoughts on contents

content/sharing.md

@@ -1,16 +1,35 @@
 # Sharing reproducible containers
 
 :::{objectives}
-- Objective 1
-- Objective 2
-- Objective 3
+- Objective 1 - Know of some key best practices for creating reproducible containers
+- Objective 2 - Know of some common version control services
+- Objective 3 - ...
 :::
 
 
-## Section
+## Reuse
+(work in progress)
+
+- Use available base containers
+- Add your customisation on top of that
 
+## Be specific
 (work in progress)
 
+- Use specific software version of everything
+- Show file with/without software versions and explain behaviour in both cases
+
+
+## Separate concerns
+(work in progress)
+- Only include things that are related to the computation and are general
+- Input-data is typically not general
+- User specific configuration 
+
+## Use version control and public registries
+- GitLab/GitHub for definition files
+- Public registry for pre-built images
+- Link the repo to the public registry
 
 ## Exercise