[DOC] Data Prepper regex and strings do not support $

[dlvenable]

What do you want to do?

• Request a change to existing documentation
• Add new documentation
• Report a technical problem with the documentation
• Other

Tell us about your request. Provide a summary of the request.

Data Prepper strings do not support $. Some pages such as the following include $ in the regex pattern, but this does not work.

https://opensearch.org/docs/latest/data-prepper/pipelines/expression-syntax/

We should remove $ from these examples.

*Version: List the OpenSearch version to which this issue applies, e.g. 2.14, 2.12--2.14, or all.

All versions

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.

Data Prepper issue to add this support:

opensearch-project/data-prepper#4772

[hdhalter]

@dlvenable, are you going to change the behavior (as per 4772) to add the support for $? If imminent, we should probably leave the docs as is. But, if it will take some time, we can remove them, and then add back once the functionality is added.