DOC-3917 added silent install docs

[andy-stark-redis]

Added docs about the silent install config file.

[github-actions]

Staging links:
https://redis.io/docs/staging/DOC-3917-silent-install-file/integrate/redis-data-integration/ingest/installation/
https://redis.io/docs/staging/DOC-3917-silent-install-file/integrate/redis-data-integration/ingest/reference/cli/redis-di-install

[yaronp68]

if you want RDI to create the db you still need to provide the RDI password to use
not sure if you always have to specify use_exisiting_rdi=false

[andy-stark-redis]

I've added some text to say that you should set use_exisiting_rdi=false because I figure it won't do any harm. We can remove this in the future if it isn't necessary.

[yaronp68]

Use this if RDI database is using TLS or mTLS

[andy-stark-redis]

Done. Also, I've commented these props out in the example TOML file (TLS/mTLS props are also commented out in the config.yaml example here: https://redis.io/docs/latest/integrate/redis-data-integration/ingest/data-pipelines/data-pipelines/#the-configyaml-file).