Gofmt at the start of the sentence should be gofmt.

[RalphCorderoy]

Commands aren't capitalised as they're case sensitive. Similarly, it remains interface when at the start of a line nearby.

[HarveyKandola]

These are as received from Rob Pike.

I think they are meant to read as proverbs and not commands.

[robpike]

English sentences start with capital letters. I disagree with your assertion here. There is no true confusion if we use English rules when writing English sentences that contain code.