Add the introduction of emitters for sdk clients.

[lirenhe]

To resolve #5339

Add the introduction to describe the location, the configuration and how to run the client emitters for Java, Python, JS and .NET.

The doc currently only contain the common content and it needs the contribution for all language owners.

cc @lmazuel

[azure-sdk]

No changes needing a change description found.

[azure-sdk]

You can try these changes here

🛝 Playground	🌐 Website	📚 Next docs	🛝 VSCode Extension

[lirenhe]

Need each language owner to update their language specific contents:

Java: @weidongxu-microsoft
JS: @MaryGao
Python: @msyyc
.NET: @JoshLove-msft

[weidongxu-microsoft]

Currently Java emitter does not have important emitter options to add.

We are checking if we need to have a (potentially cross-language) package-name emitter option. E.g. <groupdId>:<artifactId> for Java
(for azure, the <groupId> is com.azure/com.azure.resourcemanager, and <artifactId> is from SDK namespace -- but this is no longer a valid assumption for unbranded)

[lirenhe]

Currently Java emitter does not have important emitter options to add.

We are checking if we need to have a (potentially cross-language) package-name emitter option. E.g. <groupdId>:<artifactId> for Java (for azure, the <groupId> is com.azure/com.azure.resourcemanager, and <artifactId> is from SDK namespace -- but this is no longer a valid assumption for unbranded)

If there is no additional options to add, could you put some information like no additional setting needed for Java under

#### Configuration Options for Java

[lirenhe]

@JoshLove-msft, could you help to update and review the content for .NET? Thanks

[JoshLove-msft]

Is the goal of this section to list the available options or to list additional required options? If no languages have any other required options, is there any reason to retain each language option section? If the goal is to list all the additional options, then there are several other options for .NET. https://github.com/microsoft/typespec/blob/main/packages/http-client-csharp/emitter/src/options.ts#L10-L26

[timotheeguerin]

yeah +1, not sure what the point is of this section, we shouldn't have any required option to start.

[lirenhe]

The goal is to list the available options (required/optional)that customers could set in tspconfig.yaml for each language emitters.
I added those section as a place holder and let each SDK owner to decide what to include in this section.

@JoshLove-msft, if you think some of the options above are valuable for 3rd party customers to use, please include them there and provide the description, possible values, otherwise, you could remove this section for .NET.

[JoshLove-msft]

Should we link to the official documentation?

[timotheeguerin]

would be good that we include it right there on the website as well(in the same way we have docs for the other emitters)

[lirenhe]

I plan to use the readme page of each emitter,e.g.
https://www.npmjs.com/package/@typespec/http-client-csharp
However, those pages seem to be out of date which requires SDK codeGen owner to improve.

[timotheeguerin]

you can use starlight steps to hav ea nicely presented stepped tutorial https://starlight.astro.build/components/steps/

[lirenhe]

The required format in Steps would conflict with prettier check result which requires no space before code block.

[timotheeguerin]

it works fine but you have to double indent the content(then format, not sure what is the exact rule but it works), this this pr for example https://github.com/microsoft/typespec/pull/5907/files#diff-a8e95e435a79ecab53d5b97dcf924fa2e247d0d7ba63a2e27e8062731d3b1e30