[Feature Request] document max_input_length for completion type fields

[eroux]

Is your feature request related to a problem? Please describe

When I visit the documentation about the completion type fields for OpenSearch 2.15 on

https://opensearch.org/docs/latest/field-types/supported-field-types/completion/

there is no mention of the parameter max_input_length, which seems to work fine. The corresponding page in the ElasticSearch documentation does document it, along with a few other fields

Describe the solution you'd like

Please document this parameter along with other potential ones that are currently missing in the doc (like analyzer)

Related component

Search

Describe alternatives you've considered

No response

Additional context

No response

[getsaurabh02]

Thanks @eroux for bringing this up. Could you help with the PR for the documentation on this one?