Remove --static-dir type in CLIOptions

[yannbf]

Location:

storybook/code/lib/types/src/modules/core-common.ts

Line 178 in 3b94da1

staticDir?: string[];

Also, there is still a reference to the --static-dir flag in the codebase which should be removed:

storybook/code/lib/core-server/src/utils/server-statics.ts

Line 72 in 94f4361

Make sure this directory exists, or omit the {bold -s (--static-dir)} option.