Fix typos/grammar in README.md and GOVERNANCE.md

I noticed one typo in GOVERNANCE.md, and that piqued my interest enough to squash a few more too.

Feel free to mention any that I might've missed.

GOVERNANCE:

• clients configure their surfaces. (L61)
• if if (L75)
• merge in_to_, as per Gitlab's own terminology (L98)

README:

• protocols have phases (L15)
• added to the staging/ directory (L34)
• different protocol extension altogether (L40)
• missing commas and them (L61/62)
• added a link to GOVERNANCE.md just like it's done elsewhere (L246)