doc: simplify GOVERNANCE.md text

Some final simplifications for the last few paragraphs of GOVERNANCE.md.
Split a long sentence into shorter sentences. Use more consistent text.
(A nomination passes rather than "is accepted" to match language in the
previous section.)

PR-URL: https://github.com/nodejs/node/pull/27354


Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>