docs: Redefine Heading elements as below;

H1 ... Title (and might be Chapter in future)
H2 ... Section
H3 ... Subsection
H4 ... Sub-subsection

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129683 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/UsingLibraries.html b/docs/UsingLibraries.html
index 4883db2..28c1e08 100644
--- a/docs/UsingLibraries.html
+++ b/docs/UsingLibraries.html
@@ -187,12 +187,12 @@
   <!-- === This should be updated whenever new libraries are added,       ===-->
   <!-- === removed, or changed                                            ===-->
   <!-- =======NOTE: =========================================================-->
-  <h2>Dependency Relationships Of Libraries</h2>
+  <h3>Dependency Relationships Of Libraries</h3>
   <p>This graph shows the dependency of archive libraries on other archive 
   libraries or objects. Where a library has both archive and object forms, only
   the archive form is shown.</p>
   <img src="img/libdeps.gif" alt="Library Dependencies">
-  <h2>Dependency Relationships Of Object Files</h2>
+  <h3>Dependency Relationships Of Object Files</h3>
   <p>This graph shows the dependency of object files on archive libraries or 
   other objects. Where a library has both object and archive forms, only the 
   dependency to the archive form is shown.</p>