docs: fix readme typo

Author: Cweili

README.md

@@ -43,16 +43,16 @@ delve(obj, ['a', 'b', 'c']) === 1;
 delve(obj, 'a.b') === obj.a.b;
 
 //returns undefined if the full key path does not exist and no default is specified
-delve(obj, 'a.b.c.f') === undefined;
+delve(obj, 'a.b.f') === undefined;
 
 //optional third parameter for default if the full key in path is missing
-delve(obj, 'a.b.c.f', 'foo') === 'foo';
+delve(obj, 'a.b.f', 'foo') === 'foo';
 
 //or if the key exists but the value is undefined
-delve(obj, 'a.b.c.d', 'foo') === 'foo';
+delve(obj, 'a.b.d', 'foo') === 'foo';
 
 //Non-truthy defined values are still returned if they exist at the full keypath
-delve(obj, 'a.b.c.e', 'foo') === null;
+delve(obj, 'a.b.e', 'foo') === null;
 
 //undefined obj or key returns undefined, unless a default is supplied
 delve(undefined, 'a.b.c') === undefined;