update docs (#555)

* Update doxygen-gh-pages.yml

* reorganise docs folder add ref and a button to switch between dark and light, optimise doxygen

docs/docs.css

@@ -0,0 +1,95 @@
+.pagebutton {
+    display: inline-block;
+    margin-right: 1em;
+    margin-bottom: 1em;
+}
+
+html.dark-mode .pagelink {
+    display: block;
+    background-color: rgb(40, 44, 52);
+    width: 320px;
+    box-shadow: 0 0 0 0;
+    transition: 0.3s ease;
+}
+
+html.dark-mode .pagelink:hover {
+  box-shadow: 0 5px 15px 5px rgba(0,0,0,1);
+
+}
+
+.pagelink:hover img {
+  transform: scale3d(1.1,1.1,1.1);
+
+}
+
+.pageimg {
+    display: inline-block;
+    width: 100%;
+    position: relative;
+    overflow: hidden;
+}
+
+.pageimg img {
+    transition: 0.3s ease;
+}
+
+html.dark-mode .content {
+    color: white;
+    font-size: 1em;
+    padding: 0;
+    margin: 0;
+}
+
+html.dark-mode .pageheading {
+    padding: .5em .5em;
+    font-size: 18px;
+    color: white;
+    font-weight: bold;
+    text-decoration: none;
+}
+
+html.dark-mode .pagedescription {
+    color: #fff;
+    border-color: transparent;
+    opacity: 0.75;
+    height: 84px;
+    text-overflow: ellipsis;
+    overflow: hidden;
+    margin-top: 10px;
+    display: block;
+    padding: 10px;
+    text-decoration: none;
+    line-height: 1.64em;
+    font-size: 1em;
+    font-weight: normal;
+    text-decoration: none;
+}
+
+.pagea {
+    display: inline-block;
+}
+
+.pagea:link {
+    text-decoration: none;
+}
+
+.pagea:visited {
+    text-decoration: none;
+}
+
+.pagea:hover {
+    text-decoration: none;
+}
+
+.pagea:active {
+    text-decoration: none;
+}
+
+p {
+    margin: 0;
+    padding: 0;
+}
+
+html.dark-mode .clipboard {
+    fill: white;
+}