Clarify core C library version requirements.

[codonell]

Could you please update this to specify a single minimum version of glibc?

In the release page here:
https://github.com/microsoft/PowerShell-DSC-for-Linux/releases/tag/v1.2.1-0
"Glibc | GNU C Library | 2.4 - 31.30"

There is no version 31.30 of glibc, we are only about release glibc 2.34 (August 2021).

And glibc 2.4 is so old at this point that to link against a glibc 2.4 ABI you would need a special stub library (which you might have).

The minimum version is usually the version glibc of the build system that built the binaries.

For example if for maximum compatibility you build on CentOS 6 then the minimum glibc is 2.12, and you would be using that ABI baseline.

I'm happy to help work with you to determine the minimum you should actually document.