Update build instructions for bubblewrap

[tredondo]

Fixes "WARNING: Running the setup command as meson [options] instead of meson setup [options] is ambiguous and deprecated."

[charmander]

Typo (“libcap”), but libcap-dev is a distro-specific package name.

[rusty-snake]

Fedora does not provide libcap-dev, can I build bubblewrap on Fedora?
_{(Rhetorical question)}

[smcv]

Yes, that. I'd prefer a distro-neutral instruction:

Suggested change

	have `lipcap-dev` installed, then use meson:
	have `libcap` development files installed, then use meson:

or more generically

Suggested change

	have `lipcap-dev` installed, then use meson:
	have the build-time dependencies installed, then use meson:

Or just fix the meson → meson setup and don't say anything about the required libraries, because Meson will tell you if they're missing anyway, and "you need the dependencies before you can build a project" is a universal fact about building any project. It scales poorly if every project is expected to teach new developers the basics of compiling software.

[smcv]

Yes, that. I'd prefer a distro-neutral instruction:

Suggested change

	have `lipcap-dev` installed, then use meson:
	have `libcap` development files installed, then use meson:

or more generically

Suggested change

	have `lipcap-dev` installed, then use meson:
	have the build-time dependencies installed, then use meson:

Or just fix the meson → meson setup and don't say anything about the required libraries, because Meson will tell you if they're missing anyway, and "you need the dependencies before you can build a project" is a universal fact about building any project. It scales poorly if every project is expected to teach new developers the basics of compiling software.