add go install as installation option

[sombriks]

use go install results in a functional dbmate installation, as far as my tests goes.

please add this as installation option in the documentation.

[amacneil]

I don't recommend this install option:

• No guarantee that go bin is in your $PATH
• Installing "latest commit on main" is never a good idea, you want a released version
• if you happen to run this inside an existing module directory you get

$ go install github.com/amacneil/dbmate/v2
no required module provides package github.com/amacneil/dbmate/v2; to add it:
	go get github.com/amacneil/dbmate/v2

Running the proposed go get command adds a ton of unrelated dependencies to your project.

Generally I don't see any reason you would want to build dbmate from source unless you are hacking on it or using as a library. Those that are doing so should already know the appropriate commands to run.

[sombriks]

I don't recommend this install option:

• No guarantee that go bin is in your $PATH
• Installing "latest commit on main" is never a good idea, you want a released version
• if you happen to run this inside an existing module directory you get

$ go install github.com/amacneil/dbmate/v2
no required module provides package github.com/amacneil/dbmate/v2; to add it:
	go get github.com/amacneil/dbmate/v2

Running the proposed go get command adds a ton of unrelated dependencies to your project.

Generally I don't see any reason you would want to build dbmate from source unless you are hacking on it or using as a library. Those that are doing so should already know the appropriate commands to run.

i had no idea it was intentional and understand the reasons. feel free to close this PR.

[amacneil]

Also I should mention: Since we import sqlite via cgo, you will need a C toolchain installed to compile that. So ya, I highly recommend sticking to prebuilt binaries.