guide: add references to autoconf-archive, CMake and Meson

Open swilmet requested to merge swilmet/pkg-config:guide-small-update into master

The guide already contains information for use with Autotools.

Nowadays autoconf-archive contains additional macros for pkg-config (don't list them all, because the list could change, just a link to the autoconf-archive project should be enough).

Add also information about CMake and Meson.

In alphabetical order:

  • Autotools
  • CMake
  • Meson

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