docs(applicationset): explain impact of empty spec in templatePatch (a…

…rgoproj#17042)

* docs: explain impact of empty spec in templatePatch

Signed-off-by: Nicholas Morey <nicholas@morey.tech>

* fix: not conditional helm values

Signed-off-by: Nicholas Morey <nicholas@morey.tech>

---------

Signed-off-by: Nicholas Morey <nicholas@morey.tech>
Signed-off-by: penglongli <pelenli@tencent.com>

docs/operator-manual/applicationset/Template.md

@@ -111,16 +111,15 @@ In this example, the ApplicationSet controller will generate an `Application` re
 
 ## Template Patch
 
-Templating is only available on string type. However, some uses cases may require to apply templating on other types.
+Templating is only available on string type. However, some use cases may require applying templating on other types.
 
 Example:
 
-- Set the automated sync policy
-- Switch prune boolean to true
-- Add multiple helm value files
-
-Argo CD has a `templatePatch` feature to allow advanced templating. It supports both json and yaml.
+- Conditionally set the automated sync policy.
+- Conditionally switch prune boolean to `true`.
+- Add multiple helm value files from a list.
 
+The `templatePatch` feature enables advanced templating, with support for `json` and `yaml`.
 
 ```yaml
 apiVersion: argoproj.io/v1alpha1
@@ -174,3 +173,6 @@ spec:
 
     The `spec.project` field is not supported in `templatePatch`. If you need to change the project, you can use the
     `spec.project` field in the `template` field.
+
+!!! important
+    When writing a `templatePatch`, you're crafting a patch. So, if the patch includes an empty `spec: # nothing in here`, it will effectively clear out existing fields. See [#17040](https://github.com/argoproj/argo-cd/issues/17040) for an example of this behavior.