[skip ci] Use more up-to-date wording for package managers
Most of the OSes Meson supports actually do have package managers,
and at least some of them are not harder to use than Linux ones.
# Wrap dependency system manual
One of the major problems of multiplatform development is wrangling
-all your dependencies. This is easy on Linux where you can use system
-packages (and happen to know that your target distribution provides a
-recent enough version of the dependency) but awkward on other
-platforms. Most of those do not have a package manager at all. This
+all your dependencies. This is awkward on many platforms, especially
+on ones that do not have a built-in package manager. The latter problem
has been worked around by having third party package managers. They
are not really a solution for end user deployment, because you can't
tell them to install a package manager just to use your app. On these
