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

include/nlohmann/detail/conversions/to_chars.hpp

@@ -891,7 +891,7 @@ void grisu2(char* buf, int& len, int& decimal_exponent, FloatType value)
     //
     // The documentation for 'std::to_chars' (https://en.cppreference.com/w/cpp/utility/to_chars)
     // says "value is converted to a string as if by std::sprintf in the default ("C") locale"
-    // and since sprintf promotes float's to double's, I think this is exactly what 'std::to_chars'
+    // and since sprintf promotes floats to doubles, I think this is exactly what 'std::to_chars'
     // does.
     // On the other hand, the documentation for 'std::to_chars' requires that "parsing the
     // representation using the corresponding std::from_chars function recovers value exactly". That