Moving public directory away:

Moving `public/images` dir to `assets/images`, because it conflicts with gitlab CI/CD for documentation.
Moving `assets/styles.css` to `assets/styles/styles.css`.

Related to #117.

assets/images/bye.svg

@@ -0,0 +1,76 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="16"
+   height="16"
+   viewBox="0 0 4.2333332 4.2333334"
+   version="1.1"
+   id="svg1428"
+   inkscape:version="1.0.2 (e86c870879, 2021-01-15)"
+   sodipodi:docname="bye.svg"
+   inkscape:export-xdpi="9.6000004"
+   inkscape:export-ydpi="9.6000004">
+  <defs
+     id="defs1422" />
+  <sodipodi:namedview
+     id="base"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageopacity="0.0"
+     inkscape:pageshadow="2"
+     inkscape:zoom="11.2"
+     inkscape:cx="29.128627"
+     inkscape:cy="15.981622"
+     inkscape:document-units="px"
+     inkscape:current-layer="layer1"
+     inkscape:document-rotation="0"
+     showgrid="false"
+     inkscape:window-width="1851"
+     inkscape:window-height="1016"
+     inkscape:window-x="1680"
+     inkscape:window-y="27"
+     inkscape:window-maximized="1"
+     units="px" />
+  <metadata
+     id="metadata1425">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <g
+     inkscape:label="Calque 1"
+     inkscape:groupmode="layer"
+     id="layer1">
+    <rect
+       style="fill:#7d7d7d;stroke:#7d7d7d;stroke-width:0.529167;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+       id="rect1026"
+       width="4.2232938"
+       height="0.42697245"
+       x="0.8817718"
+       y="-0.21348622"
+       transform="rotate(45)"
+       ry="0.21348622" />
+    <rect
+       style="fill:#7d7d7d;stroke:#7d7d7d;stroke-width:0.529167;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+       id="rect1026-3"
+       width="4.2232938"
+       height="0.42697245"
+       x="-2.1116469"
+       y="2.7799325"
+       transform="matrix(-0.70710678,0.70710678,0.70710678,0.70710678,0,0)"
+       ry="0.21348622" />
+  </g>
+</svg>