commerce:store:create missing what defaults are for arguments

https://github.com/forcedotcom/commerce-on-lightning/tree/develop#sfdx-commercestorecreate-namevalue--n-string--t-string--f-filepath--o-string--b-string--y--v-string--u-string---apiversion-string---json---loglevel-tracedebuginfowarnerrorfataltracedebuginfowarnerrorfatal

There's no documentation on what is used for the default definitionfile if none is specified. I see that the quickstart version specifies a default: https://github.com/forcedotcom/commerce-on-lightning/tree/develop#sfdx-commercestorequickstartcreate-namevalue--n-string--t-string--u-string---apiversion-string---json---loglevel-tracedebuginfowarnerrorfataltracedebuginfowarnerrorfatal

(side note: why is the default in a hidden / dot directory in my home directory and not somewhere inside of the project like the standard sfdx-project.json location)