init command shoult use `src/index.js` as entry module by default

[montogeek]

Feature

What is the current behavior?
init command does not provide a default value for entry module.

👉  ./node_modules/.bin/webpack init

ℹ INFO For more information and a detailed description of each question, have a look at https://github.com/webpack/webpack-cli/blob/master/INIT.md
ℹ INFO Alternatively, run `webpack(-cli) --help` for usage info.

? Will your application have multiple bundles? No
? Which module will be the first to enter the application? [example: './src/index']
>> Please specify an answer!

What is the expected behavior?

init command should provide a default value src/index.js as entry module following webpack itself approach to zero configuration

[dhruvdutt]

Can we discuss this over #315 as it's quite related?

[evenstensberg]

Actually we can leave it blank by default, as 0CJS can handle it

[evenstensberg]

Just want to add that prompting that default is src/index is good to make sure users understand we're actually setting defaults.

[vijaykrishnavanshi]

Made a PR with this change.

[vijaykrishnavanshi]

Doing same for multiple bundle case also would be a good idea.
Thoughts?

[EugeneHlushko]

I am not sure you want to add something that is already default, i actually omited it in one of my PR earlier: https://github.com/webpack/webpack-cli/pull/356/files#diff-1b2b84fcd9935ef62f04b2ffd905d2c6R86