Add some sentence endings.

Doc/library/pdb.rst

@@ -269,7 +269,7 @@ n(ext)
 
 unt(il)
    Continue execution until the line with the the line number greater than the
-   current one is reached or when returning from current frame
+   current one is reached or when returning from current frame.
 
    .. versionadded:: 2.6
 

Lib/pdb.doc

@@ -130,8 +130,7 @@ n(ext)
 
 unt(il)
         Continue execution until the line with a number greater than the 
-        current one is reached or until the current frame returns
-
+        current one is reached or until the current frame returns.
 
 r(eturn)
         Continue execution until the current function returns.

Misc/NEWS

@@ -68,7 +68,7 @@ Library
 
 - os.path.walk is deprecated in favor of os.walk.
 
-- pdb gained the "until" command
+- pdb gained the "until" command.
 
 Build
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