NEWS: remove duplicated "Build" section (GH-872)

Misc/NEWS

@@ -903,6 +903,8 @@ Documentation
 Build
 -----
 
+- bpo-29643: Fix ``--enable-optimization`` didn't work.
+
 - bpo-27593: sys.version and the platform module python_build(),
   python_branch(), and python_revision() functions now use
   git information rather than hg when building from a repo.
@@ -995,11 +997,6 @@ Tools/Demos
 - Issue #28102: The zipfile module CLI now prints usage to stderr.
   Patch by Stephen J. Turnbull.
 
-Build
------
-
-- bpo-29643: Fix ``--enable-optimization`` didn't work.
-
 Tests
 -----