Connect to Astra DB - Token authentication

Hello,

I am a technical writer for DataStax. I am leaving some feedback on the [JanusGraph documentation for Astra DB](https://docs.janusgraph.org/storage-backend/cassandra/#deploying-on-datastax-astra) because I'm not sure if I need to sign the contributor agreement to submit a docs PR.

## ClientID + Secret are legacy

ClientID and secret are a [legacy authentication pattern for Astra](https://docs.datastax.com/en/astra-db-serverless/administration/manage-application-tokens.html#token-details).
The modern pattern is `token` + the application token itself (which starts with the prefix `AstraCS:..`).

The change to the documentation is minimal:
`username` is set to the literal string `token`, and `password` is set to the application token.

In janusgraph-cql.properties:

```
storage.username=token
storage.password=
```

In astra.conf:

```
username = "token"
password = ""
```

## SCB prerequisite link outdated

The sentence directing the user to download the SCB uses an old link.

In light of the above change to username/password, I suggest the following changes:

* Remove this note:

```
Note: Client id and Client secret need to be generated and copied from your Astra Account as per this [doc](https://docs.datastax.com/en/astra/docs/manage-application-tokens.html).
```

* Revise the prerequisite sentence:

```
[Download the Secure Connect Bundle (SCB)](https://docs.datastax.com/en/astra-db-serverless/databases/secure-connect-bundle.html) for your Astra database, and [generate an application token](https://docs.datastax.com/en/astra-db-serverless/administration/manage-application-tokens.html) with permission to read and write to your database.
```

## Java driver manual outdated link

Edited the issue to add that the Java driver manual link under [storage.cql.internal](https://docs.janusgraph.org/configs/configuration-reference/#storagecqlinternal) is for v 4.13 but the [pom](https://github.com/JanusGraph/janusgraph/blob/master/pom.xml#L101) has 4.17.

Note that versions 4.18+ are maintained by the ASF. Work is underway to publish documentation for 4.18+.
You can find links in the **Driver version** column here: https://docs.datastax.com/en/datastax-drivers/compatibility/java-drivers.html#java-driver-4-x-series-compatibility

Start with the linked JanusGraph Astra DB documentation and the storage.cql.internal configuration reference, then compare the current examples with the Astra token-authentication and SCB links in the issue. Check the referenced pom.xml driver version as context for the manual link. Done means the examples use token authentication, the prerequisite links and note are current, and the Java driver manual link matches the documented version.

Written by the indexing model from the issue text.