add text and examples

Signed-off-by: Melissa Vagi <[email protected]>

_ingest-pipelines/processors/set.md

@@ -37,7 +37,6 @@ Parameter | Required/Optional | Description |
 `description`  | Optional  | A brief description of the processor.
 `if` | Optional | A condition for running the processor.
 `ignore_failure` | Optional | Specifies whether the processor continues execution even if it encounters errors. If set to `true`, failures are ignored. Default is `false`.
-`ignore_missing`  | Optional  | Specifies whether the processor should ignore documents that do not contain the specified field. If set to `true`, the processor does not modify the document if the field does not exist or is `null`. Default is `false`.
 `on_failure` | Optional | A list of processors to run if the processor fails. Refer to [Handling pipeline failures]({{site.url}}{{site.baseurl}}/ingest-pipelines/pipeline-failures/).
 `override` | Optional | If `true`, the processor updates fields with pre-existing non-null-valued fields. When set to `false`, such fields are not touched. Default is `true`.
 `tag` | Optional | An identifier tag for the processor. Useful for debugging in order to distinguish between processors of the same type.