No they didn't. Webpack 2 has been kept in alpha and beta for so long exactly because the documentation was lacking. If anything that fact alone shows a good amount of maturity.

This complaint looks to me about some devs jumping to use the alpha version of v2 and got confused about which version the homepage points to. This is separate and a minor problem which they have fixed anyways.

Their versioning strategy for 2.0 was pretty poor - it hasn't actually had a proper non-alpha/beta/rc yet until now. It was precisely documentation that was holding them back from declaring 2.x as 'stable'