bpo-37970: update and improve urlparse and urlsplit doc-strings (GH-16458)

diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 34d5f95..779278b 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -366,9 +366,23 @@
 def urlparse(url, scheme='', allow_fragments=True):
     """Parse a URL into 6 components:
     <scheme>://<netloc>/<path>;<params>?<query>#<fragment>
-    Return a 6-tuple: (scheme, netloc, path, params, query, fragment).
-    Note that we don't break the components up in smaller bits
-    (e.g. netloc is a single string) and we don't expand % escapes."""
+
+    The result is a named 6-tuple with fields corresponding to the
+    above. It is either a ParseResult or ParseResultBytes object,
+    depending on the type of the url parameter.
+
+    The username, password, hostname, and port sub-components of netloc
+    can also be accessed as attributes of the returned object.
+
+    The scheme argument provides the default value of the scheme
+    component when no scheme is found in url.
+
+    If allow_fragments is False, no attempt is made to separate the
+    fragment component from the previous component, which can be either
+    path or query.
+
+    Note that % escapes are not expanded.
+    """
     url, scheme, _coerce_result = _coerce_args(url, scheme)
     splitresult = urlsplit(url, scheme, allow_fragments)
     scheme, netloc, url, query, fragment = splitresult
@@ -417,9 +431,24 @@
 def urlsplit(url, scheme='', allow_fragments=True):
     """Parse a URL into 5 components:
     <scheme>://<netloc>/<path>?<query>#<fragment>
-    Return a 5-tuple: (scheme, netloc, path, query, fragment).
-    Note that we don't break the components up in smaller bits
-    (e.g. netloc is a single string) and we don't expand % escapes."""
+
+    The result is a named 5-tuple with fields corresponding to the
+    above. It is either a SplitResult or SplitResultBytes object,
+    depending on the type of the url parameter.
+
+    The username, password, hostname, and port sub-components of netloc
+    can also be accessed as attributes of the returned object.
+
+    The scheme argument provides the default value of the scheme
+    component when no scheme is found in url.
+
+    If allow_fragments is False, no attempt is made to separate the
+    fragment component from the previous component, which can be either
+    path or query.
+
+    Note that % escapes are not expanded.
+    """
+
     url, scheme, _coerce_result = _coerce_args(url, scheme)
     allow_fragments = bool(allow_fragments)
     key = url, scheme, allow_fragments, type(url), type(scheme)