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/ProgrammersManual.html b/docs/ProgrammersManual.html
index 40013b2..e3f2a7a 100644
--- a/docs/ProgrammersManual.html
+++ b/docs/ProgrammersManual.html
@@ -2286,7 +2286,7 @@
 permits use of two very useful replace functions: <tt>ReplaceInstWithValue</tt>
 and <tt>ReplaceInstWithInst</tt>.</p>
 
-<h4><a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a></h4>
+<h5><a name="schanges_deleting">Deleting <tt>Instruction</tt>s</a></h5>
 
 <ul>
   <li><tt>ReplaceInstWithValue</tt>