doc: fix macosx-firewall suggestion BUILDING

doc: fix macosx-firewall suggestion BUILDING · nodejs/node@699cfa1

Original file line number	Diff line number	Diff line change
@@ -91,7 +91,7 @@ On macOS you will need to install the `Xcode Command Line Tools` by running
`91`	`91`	installed, you can find them under the menu `Xcode -> Open Developer Tool ->
`92`	`92`	More Developer Tools...`. This step will install `clang`, `clang++`, and
`93`	`93`	`make`.
`94`		`-* You may want to setup [firewall rules](tools/macosx-firewall.sh)`
	`94`	`+* After building, you may want to setup [firewall rules](tools/macosx-firewall.sh)`
`95`	`95`	`to avoid popups asking to accept incoming network connections when running tests:`
`96`	`96`
`97`	`97`	`If the path to your build directory contains a space, the build will likely fail.`