JGC-473 - Fix --delete-properties separator in version-update help

Addresses review from @shayshim:
- version-update AIDescription: --delete-properties is parsed by
  utils.ParseSliceFlag, which splits on ';' (not ','). Fixed the example
  ("env,owner" -> "env;owner") and the gotcha ("comma-separated" ->
  "semicolon-separated"); a comma-joined value was treated as one literal key.
- Corrected the pre-existing inaccurate doc comment on ParseSliceFlag in
  utils.go ("comma-separated" -> "semicolon-separated").

Author: ehl-jf

apptrust/commands/utils/utils.go

@@ -41,7 +41,7 @@ func ServerDetailsByFlags(ctx *components.Context) (*coreConfig.ServerDetails, e
 	return serverDetails, nil
 }
 
-// ParseSliceFlag parses a comma-separated string into a slice of strings.
+// ParseSliceFlag parses a semicolon-separated string into a slice of strings.
 func ParseSliceFlag(flagValue string) []string {
 	if flagValue == "" {
 		return []string{}

apptrust/commands/version/update_app_version_cmd.go

@@ -137,13 +137,13 @@ Prerequisites:
 Common patterns:
   $ jf apptrust version-update my-app 1.0.0 --tag=stable
   $ jf apptrust version-update my-app 1.0.0 --properties="env=prod;owner=team-a,team-b"
-  $ jf apptrust version-update my-app 1.0.0 --delete-properties="env,owner"
+  $ jf apptrust version-update my-app 1.0.0 --delete-properties="env;owner"
   $ jf apptrust version-update my-app 1.0.0 --tag=stable --properties="release-notes=https://example.com/notes"
 
 Gotchas:
 - --properties replaces values for the specified keys; other keys are untouched.
 - --properties uses semicolons to separate key=value pairs and commas to separate multiple values for a single key: key1=v1,v2;key2=v3.
-- --delete-properties takes a comma-separated list of keys and removes those keys entirely.
+- --delete-properties takes a semicolon-separated list of keys and removes those keys entirely.
 - This command does not change sources or promotion stage; use version-update-sources or version-promote for those.
 
 Related: jf apptrust version-update-sources, jf apptrust version-create`,