docs: Fix minor grammar issue in shortcodes.md
docs: Fix minor grammar issue in shortcodes.md


gohugoio/hugo,mdhender/hugo,digitalcraftsman/hugo,fedelibre/hugo,fedelibre/hugo,gohugoio/hugo,fedelibre/hugo,mitchchn/hugo,anthonyfok/hugo,gohugoio/hugo,anthonyfok/hugo,mdhender/hugo,mdhender/hugo,fedelibre/hugo,mdhender/hugo,anthonyfok/hugo,digitalcraftsman/hugo,mitchchn/hugo