Support finding a local yamlfmt config file named `.yamlfmt.yaml`

[Nogweii]

Add an additional filename that can be found (or maybe two, with both variations of the extension). It'd be nice if ~/code/foobar/.yamlfmt.yaml was loaded, as that would means editors will easily detect the file type.

[Braydon Kains]

Hi @nogweii,

v0.11.0 added support for calling the file yamlfmt.yml or yamlfmt.yaml. I opened a PR so those can be hidden as well.