📝 update documentation (#4723)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

docs/mkdocs/docs/features/element_access/default_value.md

@@ -2,7 +2,7 @@
 
 ## Overview
 
-In many situations such as configuration files, missing values are not exceptional, but may be treated as if a default
+In many situations, such as configuration files, missing values are not exceptional, but may be treated as if a default
 value was present. For this case, use [`value(key, default_value)`](../../api/basic_json/value.md) which takes the key
 you want to access and a default value in case there is no value stored with that key.
 

docs/mkdocs/docs/features/element_access/unchecked_access.md

@@ -29,7 +29,7 @@ similar to a `#!cpp std::map` and a `#!cpp std::vector`, respectively.
     | `#!cpp j["hobbies"][1]` | `#!json "reading"`                                                           |
 
 The return value is a reference, so it can modify the original value. In case the passed object key is non-existing, a
-`#!json null` value is inserted which can be immediately be overwritten.
+`#!json null` value is inserted which can immediately be overwritten.
 
 ??? example "Write access"