Consolidate documentation (#3071)

* 🔥 consolidate documentation
* ♻️ overwork std specializations
* 🚚 move images files to mkdocs
* ♻️ fix URLs
* 🔧 tweak MkDocs configuration
* 🔧 add namespaces
* 📝 document deprecations
* 📝 document documentation generation
* 🚸 improve search
* 🚸 add examples
* 🚧 start adding documentation for macros
* 📝 add note for https://github.com/nlohmann/json/issues/874#issuecomment-1001699139
* 📝 overwork example handling
* 📝 fix Markdown tables

doc/mkdocs/docs/api/json_sax/end_array.md

@@ -0,0 +1,15 @@
+# <small>nlohmann::json_sax::</small>end_array
+
+```cpp
+virtual bool end_array() = 0;
+```
+
+The end of an array was read.
+
+## Return value
+
+Whether parsing should proceed.
+
+## Version history
+
+- Added in version 3.2.0.