Mentioned proper credentials file location for non-Windows

[tylercollier]

No description provided.

[coveralls]

Coverage increased (+0.15%) when pulling 35cc61f on tylercollier:develop into 0204b80 on aws:develop.

[jamesls]

The ~/.aws/config file is where these config values should be placed. The ~/.aws/credentials file will only accept access/secret key vars, and the sample config snippet above contains additional things like the region to use. There's a proposal to better integrate with this file (#847), and once that's implemented we can update the README appropriately.

[tylercollier]

Ok. When I put my settings in ~/.aws/config, it didn't work, and I got no warning message like "Your config or credentials file is missing". By putting them in ~/.aws/credentials, it worked.

[tylercollier]

Dear future self: My problem was not reading carefully enough. In the readme, it shows how to name a profile. I neglected to actually use the word profile in [profile <my profile name>].

@jamesls: This is a comment for #847 (I'm not sure if I'm welcome to comment there as I'm not a contributor or anything): My question is can you set up multiple profiles in the ~/.aws/credentials file?