Reorganize directories (#3462)

* 🚚 move files
* 🚚 rename doc folder to docs
* 🚚 rename test folder to tests

docs/mkdocs/docs/api/basic_json/from_bson.md

@@ -0,0 +1,110 @@
+# <small>nlohmann::basic_json::</small>from_bson
+
+```cpp
+// (1)
+template<typename InputType>
+static basic_json from_bson(InputType&& i,
+                            const bool strict = true,
+                            const bool allow_exceptions = true);
+// (2)
+template<typename IteratorType>
+static basic_json from_bson(IteratorType first, IteratorType last,
+                            const bool strict = true,
+                            const bool allow_exceptions = true);
+```
+
+Deserializes a given input to a JSON value using the BSON (Binary JSON) serialization format.
+
+1. Reads from a compatible input.
+2. Reads from an iterator range.
+
+The exact mapping and its limitations is described on a [dedicated page](../../features/binary_formats/bson.md).
+
+## Template parameters
+
+`InputType`
+:   A compatible input, for instance:
+    
+    - an `std::istream` object
+    - a `FILE` pointer
+    - a C-style array of characters
+    - a pointer to a null-terminated string of single byte characters
+    - an object `obj` for which `begin(obj)` and `end(obj)` produces a valid pair of iterators.
+
+`IteratorType`
+:   a compatible iterator type
+
+## Parameters
+
+`i` (in)
+:   an input in BSON format convertible to an input adapter
+
+`first` (in)
+:   iterator to start of the input
+
+`last` (in)
+:   iterator to end of the input
+
+`strict` (in)
+:   whether to expect the input to be consumed until EOF (`#!cpp true` by default)
+
+`allow_exceptions` (in)
+:   whether to throw exceptions in case of a parse error (optional, `#!cpp true` by default)
+
+## Return value
+
+deserialized JSON value; in case of a parse error and `allow_exceptions` set to `#!cpp false`, the return value will be
+`value_t::discarded`.  The latter can be checked with [`is_discarded`](is_discarded.md).
+
+## Exception safety
+
+Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
+
+## Exceptions
+
+Throws [`parse_error.114`](../../home/exceptions.md#jsonexceptionparse_error114) if an unsupported BSON record type is
+encountered.
+
+## Complexity
+
+Linear in the size of the input.
+
+## Examples
+
+??? example
+
+    The example shows the deserialization of a byte vector in BSON format to a JSON value.
+     
+    ```cpp
+    --8<-- "examples/from_bson.cpp"
+    ```
+    
+    Output:
+    
+    ```json
+    --8<-- "examples/from_bson.output"
+    ```
+
+## See also
+
+- [BSON specification](http://bsonspec.org/spec.html)
+- [to_bson](to_bson.md) for the analogous serialization
+- [from_cbor](from_cbor.md) for the related CBOR format
+- [from_msgpack](from_msgpack.md) for the related MessagePack format
+- [from_ubjson](from_ubjson.md) for the related UBJSON format
+
+## Version history
+
+- Added in version 3.4.0.
+
+!!! warning "Deprecation"
+
+    - Overload (2) replaces calls to `from_bson` with a pointer and a length as first two parameters, which has been
+      deprecated in version 3.8.0. This overload will be removed in version 4.0.0. Please replace all calls like
+      `#!cpp from_bson(ptr, len, ...);` with `#!cpp from_bson(ptr, ptr+len, ...);`.
+    - Overload (2) replaces calls to `from_bson` with a pair of iterators as their first parameter, which has been
+      deprecated in version 3.8.0. This overload will be removed in version 4.0.0. Please replace all calls like
+      `#!cpp from_bson({ptr, ptr+len}, ...);` with `#!cpp from_bson(ptr, ptr+len, ...);`.
+
+    You should be warned by your compiler with a `-Wdeprecated-declarations` warning if you are using a deprecated
+    function.