[docs] Convert docs index page into Sphinx.

- Work in progress, this is mostly important because it lets us incrementally migrate the remaining documentation.
 - Lots of styling, editing, and integration work yet to come…
 - PR12589

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155133 91177308-0d34-0410-b5e6-96231b3b80d8

docs/TestingGuide.html

@@ -626,6 +626,8 @@ define i8 @coerce_offset0(i32 %V, i32* %P) {
 
 <div>
 
+<!-- {% raw %} -->
+
 <p>The CHECK: and CHECK-NOT: directives both take a pattern to match.  For most
 uses of FileCheck, fixed string matching is perfectly sufficient.  For some
 things, a more flexible form of matching is desired.  To support this, FileCheck
@@ -650,6 +652,8 @@ braces like you would in C.  In the rare case that you want to match double
 braces explicitly from the input, you can use something ugly like
 <b>{{[{][{]}}</b> as your pattern.</p>
 
+<!-- {% endraw %} -->
+
 </div>
 
 <!-- _______________________________________________________________________ -->
@@ -659,6 +663,9 @@ braces explicitly from the input, you can use something ugly like
 
 <div>
 
+
+<!-- {% raw %} -->
+
 <p>It is often useful to match a pattern and then verify that it occurs again
 later in the file.  For codegen tests, this can be useful to allow any register,
 but verify that that register is used consistently later.  To do this, FileCheck
@@ -690,6 +697,8 @@ that FileCheck is not actually line-oriented when it matches, this allows you to
 define two separate CHECK lines that match on the same line.
 </p>
 
+<!-- {% endraw %} -->
+
 </div>
 
 </div>