Error on the example for Backends and vhosts

The example for 'Backends and virtual hosts' contains an error: It says 'or' instead of '||'.

This is the error you get:
```
Message from VCC-compiler:
Expected ')' got 'or'
(program line 69), at
('input' Line 79 Pos 43)
        if (req.http.host == "foo.com" or req.http.host == "www.foo.com") {
------------------------------------------##-------------------------------------

Running VCC-compiler failed, exit 1

VCL compilation failed
```