Fixed broken links in the README file

README.md

@@ -1265,10 +1265,10 @@ The library is currently used in Apple macOS Sierra and iOS 10. I am not sure wh
 
 ## Notes
 
-- The code contains numerous debug **assertions** which can be switched off by defining the preprocessor macro `NDEBUG`, see the [documentation of `assert`](https://en.cppreference.com/w/cpp/error/assert). In particular, note [`operator[]`](https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a2e26bd0b0168abb61f67ad5bcd5b9fa1.html#a2e26bd0b0168abb61f67ad5bcd5b9fa1) implements **unchecked access** for const objects: If the given key is not present, the behavior is undefined (think of a dereferenced null pointer) and yields an [assertion failure](https://github.com/nlohmann/json/issues/289) if assertions are switched on. If you are not sure whether an element in an object exists, use checked access with the [`at()` function](https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a674de1ee73e6bf4843fc5dc1351fb726.html#a674de1ee73e6bf4843fc5dc1351fb726).
-- As the exact type of a number is not defined in the [JSON specification](http://rfc7159.net/rfc7159), this library tries to choose the best fitting C++ number type automatically. As a result, the type `double` may be used to store numbers which may yield [**floating-point exceptions**](https://github.com/nlohmann/json/issues/181) in certain rare situations if floating-point exceptions have been unmasked in the calling code. These exceptions are not caused by the library and need to be fixed in the calling code, such as by re-masking the exceptions prior to calling library functions.
+- The code contains numerous debug **assertions** which can be switched off by defining the preprocessor macro `NDEBUG`, see the [documentation of `assert`](https://en.cppreference.com/w/cpp/error/assert). In particular, note [`operator[]`](https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a233b02b0839ef798942dd46157cc0fe6.html#a233b02b0839ef798942dd46157cc0fe6) implements **unchecked access** for const objects: If the given key is not present, the behavior is undefined (think of a dereferenced null pointer) and yields an [assertion failure](https://github.com/nlohmann/json/issues/289) if assertions are switched on. If you are not sure whether an element in an object exists, use checked access with the [`at()` function](https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a73ae333487310e3302135189ce8ff5d8.html#a73ae333487310e3302135189ce8ff5d8).
+- As the exact type of a number is not defined in the [JSON specification](https://tools.ietf.org/html/rfc7159.html), this library tries to choose the best fitting C++ number type automatically. As a result, the type `double` may be used to store numbers which may yield [**floating-point exceptions**](https://github.com/nlohmann/json/issues/181) in certain rare situations if floating-point exceptions have been unmasked in the calling code. These exceptions are not caused by the library and need to be fixed in the calling code, such as by re-masking the exceptions prior to calling library functions.
 - The library supports **Unicode input** as follows:
-  - Only **UTF-8** encoded input is supported which is the default encoding for JSON according to [RFC 7159](http://rfc7159.net/rfc7159#rfc.section.8.1).
+  - Only **UTF-8** encoded input is supported which is the default encoding for JSON according to [RFC 7159](https://tools.ietf.org/html/rfc7159.html#section-8.1).
   - Other encodings such as Latin-1, UTF-16, or UTF-32 are not supported and will yield parse or serialization errors.
   - [Unicode noncharacters](http://www.unicode.org/faq/private_use.html#nonchar1) will not be replaced by the library.
   - Invalid surrogates (e.g., incomplete pairs such as `\uDEAD`) will yield parse errors.