[Docs] Fix opType options in IndexRequest API example. (#48290)

Author: AlexJF

docs/java-rest/high-level/document/index.asciidoc

@@ -85,7 +85,7 @@ include-tagged::{doc-tests-file}[{api}-request-version-type]
 include-tagged::{doc-tests-file}[{api}-request-op-type]
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 <1> Operation type provided as an `DocWriteRequest.OpType` value
-<2> Operation type provided as a `String`: can be `create` or `update` (default)
+<2> Operation type provided as a `String`: can be `create` or `index` (default)
 
 ["source","java",subs="attributes,callouts,macros"]
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