Make a pull request (PR).
Upon successful review, someone will give the PR a LGTM (looks good to me) in the review thread.
A SIG lead (or someone with approval powers as specified in an OWNERS file) may merge the PR immediately with or without an LGTM from someone else. Or they may wait a business day to get further feedback from other reviewers.
Edits in SIG sub-directories should follow any additional guidelines described
by the respective SIG leads in the sub-directory's CONTRIBUTING file
(e.g. sig-cli/CONTRIBUTING).