SplitChunks.name: Specify that setting a specific name merges all chunks in one file

[pherrymason]

Feature to document
Based on @sokra comment here, setting splitChunks.name to a string will merge all chunks into a single one.
This is not documented here: webpack/webpack#8582 (comment)

Author(s)
?

Additional information
The docs document properly other "edge" cases as:

If the name matches an entry point name, the entry point will be removed.

But it caught me out of guard that setting a name generated one single chunk, so I guess it would be useful to have this case documented too.

[EugeneHlushko]

For sure, want to file a PR @raulferras ?

[yaaooo]

Hey @raulferras I've filed a PR for this