add basic README

README.md

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+# Buddhabrot
+
+This is a very simple binary to create images of the [Mandelbrot
+set](https://en.wikipedia.org/wiki/Mandelbrot_set) and [Buddhabrot
+set](https://en.wikipedia.org/wiki/Buddhabrot). The final goal is to use the
+[Metropolis-Hastings sampling
+algorithm](https://en.wikipedia.org/wiki/Metropolis%E2%80%93Hastings_algorithm)
+and [Simulated Annealing](https://en.wikipedia.org/wiki/Simulated_annealing).
+
+## Building the project
+
+You need [Meson](https://mesonbuild.com/) to build the project, and I recommend
+using [Ninja](https://ninja-build.org/) as a build system. Issue the following
+commands:
+
+```sh
+42sh$ meson build
+42sh$ ninja -C build
+```
+
+This compiles the `buddhabrot` binary at the root of the `build` directory.
+
+## Using the binary
+
+By default, the binary writes the output image to its standard output, in the
+[PPM file format](http://netpbm.sourceforge.net/doc/ppm.html).
+
+You can choose which visualisation you want by using the `-r` options with
+either `buddhabrot` or `mandelbrot`. Use `-m` to choose the maximum number of
+iterated samples.
+
+You can specify the height and width of the image by using `-h` and `-w`.
+
+Sample usage:
+
+```sh
+42sh$ ./buddhabrot -r buddhabrot -o out.ppm  -m 1000 -h 1080 -w 1920
+```
+
+## Creating images
+
+The binary outputs a grayscale image of the buddhabrot for the given sampling
+rate.
+
+The project's logo has been created by outputting three different buddhabrot
+sets for `100`, `1000`, and `10000` samples. Once done, use the following
+command to create the image (using
+[ImageMagick](https://imagemagick.org/index.php)).
+
+```sh
+42sh$ convert \
+    10000.ppm -channel R \
+    1000.ppm -channel G \
+    100.ppm -channel B \
+    -combine -channel RGB \
+    -alpha off -colorspace sRGB \
+    out.png
+```