[DOCS] Fix cache setting name in 7.9 migration docs (#64063) (#64073)

The setting name is script.context.$CONTEXT.cache_max_size rather than
script.context.$CONTEXT.context_max_size.

Co-authored-by: Andrew Kroh <[email protected]>

Author: jrodewig

docs/reference/migration/migrate_7_9.asciidoc

@@ -59,8 +59,8 @@ set per-context.
 
 *Impact* +
 To avoid deprecation warnings, discontinue use of the `script.cache.max_size`
-setting. You may use `script.context.$CONTEXT.context_max_size` for the particular context.
-For example, for the `ingest` context, use `script.context.ingest.context_max_size`.
+setting. You may use `script.context.$CONTEXT.cache_max_size` for the particular context.
+For example, for the `ingest` context, use `script.context.ingest.cache_max_size`.
 
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