design/43651-type-parameters: minor formatting/wording fixes
design/43651-type-parameters: minor formatting/wording fixes

Change-Id: I3eba2d2d24c23d8c9e371ea1a123be32ae84cbaa
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/352114
Trust: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

golang/proposal,golang/proposal