README.md: added an installation section

Author: vmagnin

README.md

@@ -4,6 +4,55 @@ This repository contains the libcairo bindings for Fortran from the [gtk-fortran
 
 Remark: it was cloned from the now unavailable @brocolis' repository (latest 5th September 2021 version).
 
+## Requirements and dependencies
+
+You need:
+
+* a modern Fortran compiler, for example GFortran or the Intel ifort/ifx compilers. See the [Fortran-lang.org compilers page](https://fortran-lang.org/compilers/) for other compilers.
+* The Cairo development files (`libcairo2-dev` package in Ubuntu).
+* The Fortran Package Manager [fpm](https://fpm.fortran-lang.org/).
+
+### Installation in Linux
+
+For example, in Ubuntu:
+```bash
+$ sudo apt install gfortran libcairo2-dev
+```
+
+Concerning fpm, see the [fpm documentation](https://fpm.fortran-lang.org/en/install/index.html).
+
+If you have a GitHub account, just clone the repository:
+
+```
+$ git clone git@github.com:vmagnin/cairo-fortran.git
+$ cd cairo-fortran
+```
+
+### Installation in Windows
+
+You can use for example the [MSYS2](http://www.msys2.org/) environment:
+* https://packages.msys2.org/base/mingw-w64-cairo
+* https://packages.msys2.org/base/mingw-w64-fpm
+
+Install the following packages via the MSYS2-MSYS shell:
+  * build tools: 
+    * `$ pacman -S mingw-w64-ucrt-x86_64-toolchain base-devel` (it will install gcc, gdb, gfortran, python, make, pkgconf...)
+  * git: 
+    * `$ pacman -S git`
+  * Cairo and its dependencies: 
+    * `$ pacman -S mingw-w64-ucrt-x86_64-cairo`
+  * Fortran Package Manager fpm: 
+    * `$ pacman -S mingw-w64-ucrt-x86_64-fpm`
+
+Then start the MSYS2-UCRT64 shell.
+
+If you have a GitHub account, just clone the repository:
+
+```
+$ git clone git@github.com:vmagnin/cairo-fortran.git
+$ cd cairo-fortran
+```
+
 ## Testing cairo-fortran
 
 Each test prints nothing in the terminal but is creating a PNG file. You should therefore obtain three PNG files in the main directory of the project:
@@ -49,7 +98,7 @@ GPL-3.0-or-later
 * API Reference Manual: https://cairographics.org/manual/
 
 
-## Original project and Authors
+## Original project
 * Origin: [gtk-fortran project](https://github.com/vmagnin/gtk-fortran/)
 * Authors:
 > Vincent MAGNIN, James TAPPIN, Jens HUNGER, Jerry DE LISLE, "gtk-fortran: a GTK+ binding to build Graphical User Interfaces in Fortran", _Journal of Open Source Software,_ 4(34), 1109, 12th January 2019, [https://doi.org/10.21105/joss.01109](https://doi.org/10.21105/joss.01109)