Fixup documentation

- better gomarkdown generation that now fixed the escaped strings, no
  need to use pandoc anymore
- added workflow image
- upgraded versions of mkdocs requirements

doc/requirements.txt

@@ -1,6 +1,6 @@
-mkdocs>=1.3.0
-Jinja2>=2.10.2
-MarkupSafe>=2.0
-pymdown-extensions>=9.5
-mkdocs-material>=8.3.4
-mkdocs-material-extensions>=1.0.3
+mkdocs>=1.5.3
+Jinja2>=3.1.3
+MarkupSafe>=2.1.5
+pymdown-extensions>=10.7.1
+mkdocs-material>=9.5.17
+mkdocs-material-extensions>=1.3.1