[#74316] document JSON WP workflows

Add README examples for the new machine-readable Work Package
flows: inspect with children, parent-aware create dry-runs, and
schema-driven update dry-runs.

https://community.openproject.org/projects/cli/work_packages/74316

Author: myabc

README.md

@@ -150,6 +150,10 @@ op create workpackge --project 11 'Document new CLI tool'
 
 # Same command with shorthands and directly open it in a browser to continue working on it.
 op create workpackge -p11 'Document new CLI tool' -o
+
+# Validating the creation of a child work package without persisting it.
+# The parent determines the project automatically.
+op create workpackage --parent 74316 --type Implementation 'Build reusable skill' --dry-run --json
 ```
 
 #### Listing
@@ -174,6 +178,9 @@ op update workpackage 42 --subject 'The new subject' --status 'In Progress' --ty
 
 # Uploading an attachment to a work package
 op update workpackage 42 --attach ./Downloads/Report.pdf
+
+# Resolving and validating field updates as JSON before applying them
+op update workpackage 74316 --set 'Votes=3' --dry-run --json
 ```
 
 #### Inspecting
@@ -182,6 +189,9 @@ op update workpackage 42 --attach ./Downloads/Report.pdf
 # Inspecting a work package with more details,
 # then in the work package list command
 op inspect workpackage 42
+
+# Inspecting a work package and its direct children as machine-readable JSON
+op inspect workpackage 74316 --children --json
 ```
 
 ## Creating a release