Feature/mkdocs with versioning (#333)

* docs: restructuring & introduction of mkdocs with versioning provided by mike

* docs: ad repositories section to sophia examples

* docs: refactoring and consistent naming of æternity

* docs: hint for new file destination

* docs: revert capital letter

* docs: accept proposed changes

* docs: fix anchors in stdlib

.docssite/hook.py

@@ -0,0 +1,7 @@
+import glob
+import shutil
+
+def pre_build(**kwargs):
+  for file in glob.glob('../docs/*.md'):
+    shutil.copy(file, 'docs')
+  shutil.copy('../CHANGELOG.md', 'docs')