Dependencies inconsistent with `crun`

Currently, the [installation instructions for building Podman from source][building] say that `pkg-config` is a prerequisite for building Podman on Ubuntu, but they [also suggest][crun] that it may be necessary to build `crun` or `runc` from source if the version isn't recent enough (which in my case it wasn't) – and the build instructions for `crun` [state that `pkgconf`][pkgconf] needs to be installed to build crun.

At least on Ubuntu 20.04, it's not possible to have both `pkgconf` and `pkg-config` installed at the same time. Is `pkgconf` sufficient for building Podman, or do I have to install `pkgconf`, build `crun`, then uninstall `pkgconf` and install `pkg-config` before I build Podman?

I also wondered why there was this inconsistency, when both Podman and `crun` are projects in the [containers](https://github.com/containers) GitHub organisation – should one or the other be amended so that they're both the same?

[building]: https://github.com/containers/podman.io/blob/2a159abffab6e59efc61fc9f5c1c0772cfb44f56/getting-started/installation.md?plain=1#L352
[crun]: https://github.com/containers/podman.io/blob/2a159abffab6e59efc61fc9f5c1c0772cfb44f56/getting-started/installation.md?plain=1#L428
[pkgconf]: https://github.com/containers/crun/blob/4934df988f4c039455cfa397109a24cd82f04783/README.md?plain=1#L91

Compare getting-started/installation.md at the linked building and crun sections with the crun README at the linked pkgconf section. First verify whether pkgconf satisfies Podman's Ubuntu 20.04 build requirements, then update the relevant installation guidance so the dependency instructions agree and clearly describe the required packages.

Written by the indexing model from the issue text.