docs: update incorrect batch size reference

[RahulLanjewar93]

In current parse-server, I dont think there is a cap for how many objects can be updated/saved/destroyed in one go.
So maybe we should update this in docs.

[mtrezza]

• What is the current batch size limit?
• Is this the only place where this limit is mentioned in the docs?

[RahulLanjewar93]

• The current batch size is 20. REQUEST_BATCH_SIZE: 20 https://github.com/parse-community/Parse-SDK-JS/blob/10a2e5b02db62bdb5edd996ff05198cd96d127f5/src/CoreManager.js#L187
• I am not sure , but I think batch endpoints are not mentioned in other platforms

[RahulLanjewar93]

Also, there is this PR on how to use transactions on client sdks while using the batch endpoint.
It's not merged yet and somewhere they did mention removing the batch size and putting everything in a single batch because it's causing issues.

[mtrezza]

If the current batch size is 20, not 50, should that be mentioned in the docs instead of removing the note altogether?

[RahulLanjewar93]

@mtrezza the batch size is customizable in the JS SDK. The default is set to 20.

[mtrezza]

Looks good!