readme.md: added MacPorts to packages list [skip ci] (#7168)

Author: firewave

readme.md

@@ -274,7 +274,8 @@ Unofficial packages *not* maintained by the Cppcheck team but their respective p
 - (Linux/Unix) Many major distros offer Cppcheck packages via their integrated package managers (`yum`, `apt`, `pacman`, etc.). See https://pkgs.org/search/?q=cppcheck for an overview.
 - (Linux/Unix) Unless you are using a "rolling" distro, it is likely that they are not carrying the latest version. There are several external (mainly unsupported) repositories like AUR (ArchLinux), PPA (ubuntu), EPEL (CentOS/Fedora) etc. which might provide up-to-date packages. 
 - (Linux/Unix / Outdated) The Canonical Snapcraft packages (https://snapcraft.io/cppcheck / https://snapcraft.io/cppcheckgui) are unmaintained and contain very old (development) versions. Please refrain from using them! See https://trac.cppcheck.net/ticket/11641 for more details.
-- (MacOS) A package is available via Homebrew (`brew`). See https://formulae.brew.sh/formula/cppcheck#default.
+- (MacOS) A package is available via Homebrew (`brew`). See https://formulae.brew.sh/formula/cppcheck.
+- (MacOS) A package is available via https://ports.macports.org/port/cppcheck/
 - (Multi-Platform) A package is available via https://anaconda.org/conda-forge/cppcheck.
 - Packages are also available from various download portals (mainly the Windows installer - sometimes re-packaged).