Referenced readme in cprover docs

The links were not relative, so updated to be relative. Mentioned that
you can find more in the readme.

Author: Thomas Kiley

doc/cprover-manual/cbmc-tutorial.md

@@ -138,9 +138,11 @@ possible output format.
 ```
 
 The specification of the XML trace output can be found here: [XML
-Specification](https://raw.githubusercontent.com/diffblue/cbmc/develop/doc/assets/xml_spec.tex)
-and can be build by `pdflatex -shell-escape xml_spec.tex`. Alternatively, you
-view it in Markdown [here](../../../assets/xml_spec).
+Specification](../assets/xml_spec.tex)
+and can be build by `pdflatex -shell-escape xml_spec.tex`. See the [README
+](../assets/README.md#xml_spec.tex) for details.
+
+Alternatively, you view it in [Markdown](../assets/xml_spec.md).
 
 ### Verifying Modules