Add Meson build instructions

Also fix CMake instructions indent level

Author: Ericson2314

README.md

@@ -81,7 +81,7 @@ make check
 sudo make install
 ```
 
-## Via [CMake](https://cmake.org/) (and [Ninja](https://ninja-build.org/))
+### Via [CMake](https://cmake.org/) (and [Ninja](https://ninja-build.org/))
 
 ```console
 mkdir build
@@ -91,6 +91,16 @@ ninja all
 sudo ninja install
 ```
 
+### Via [Meson](https://mesonbuild.com/) (and [Ninja](https://ninja-build.org/))
+
+```console
+mkdir build
+meson configure build
+cd build
+ninja all
+sudo ninja install
+```
+
 ### Via Nix
 
 You can build with Nix in several ways.