Fix typo 'typdefs', from Nikola Smiljanic

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146894 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/InternalsManual.html b/docs/InternalsManual.html
index 46041c4..0df1e32 100644
--- a/docs/InternalsManual.html
+++ b/docs/InternalsManual.html
@@ -928,7 +928,7 @@
 <p>Representing types like this is great for diagnostics, because the
 user-specified type is always immediately available.  There are two problems
 with this: first, various semantic checks need to make judgements about the
-<em>actual structure</em> of a type, ignoring typdefs.  Second, we need an
+<em>actual structure</em> of a type, ignoring typedefs.  Second, we need an
 efficient way to query whether two types are structurally identical to each
 other, ignoring typedefs.  The solution to both of these problems is the idea of
 canonical types.</p>