A breaking change was introduced by mistake

[ImSingee]

What version of GCI are you using?

v0.10.1

Reproduce Steps

1. Run `gci write -s 'standard,default' path1` which is valid in old versions
2. An error occurred

What did you expect to see?

It should work as before

Some notes

This is because, in PR #142, the type of the Section flag is changed from StringSlice to StringArray. The previous one allows --flag A,B to be seen as equal to --flag A --flag B but the latter does not.

There are at least two ways to optimize the situation:

1. Change the new syntax Prefix(A,B) to Prefix(A|B) (or something similar) which does not require a breaking change to existing usage
2. Mark the v0.10.0 release as a breaking change

However, both are not done; a breaking change is silently introduced.

Because v0.10.0 is also released, so I think it may not good to change the new prefix grammar. But at least, this change should be highlighted in the v0.10.0 release.

[daixiang0]

@ImSingee good catch! Could you help update README then I will create a new release to highlight it?