Updated readme file with instructions on how to set compound attributes and delete them.

README.md

@@ -49,6 +49,37 @@ git push -uf origin main
 ## Metadata review workflow
     - review through branches
     - updating files with metadata in Openbis
+### Specifying a compound attribute in yaml language.
+Consider the compound attribute *relative_humidity*, which has subattributes *value*, *units*, *range*, and *definition*. The yaml description of
+such an attribute is as follows:
+```yaml
+relative_humidity:
+  value: 65
+  units: percentage
+  range: '[0,100]'
+  definition: 'Relative humidity represents the amount of water vapor present in the air relative to the maximum amount of water vapor the air can hold at a given temperature.'  
+```
+### Deleting or renaming a compound attribute in yaml language.
+  - When the attribute is existing, it should be displayed as follows with the subattribute *rename_as*, which can be modified as desired.
+  - deleting an attribute on the other hand requires to add a subattribute called *delete* with the value *true*. In the below example, the
+  attribute relative humidity is suggested to be removed. if *delete* is set as *false* it will have no effect.
+```yaml
+relative_humidity:
+  delete: true # we added this line in the review process
+  rename_as: relative_humidity
+  value: 65
+  units: percentage
+  range: '[0,100]'
+  definition: 'Relative humidity represents the amount of water vapor present in the air relative to the maximum amount of water vapor the air can hold at a given temperature.'
+
+```
+
+```
+cd existing_repo
+git remote add origin https://gitlab.psi.ch/5505/functionspython.git
+git branch -M main
+git push -uf origin main
+```
 
 ## Integrate with your tools