Dynare++ documentation updates

— no longer say that Dynare is limited to 3rd order
— drop obsolete internal documentations of numerical integration and k-order
  modules
— update the remaining PDFs

resources/index.md

@@ -158,7 +158,7 @@ Various bits of information such as [new](https://git.dynare.org/Dynare/dynare/w
 Originally written by Ondra Kamenik, Dynare++ is a C++ library that computes
 higher order approximations of DSGE models via a perturbation method. It is
 available as a standalone executable program (shipped with the Dynare
-installer) and is also used by Dynare to compute third order approximations.
+installer) and is also used by Dynare to compute higher order approximations.
 
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@@ -181,13 +181,5 @@ a description of the algorithm used for [solving the specialized Sylvester equat
 </p>
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-the internal documentation of the [numerical integration module](../assets/dynare++/integ.pdf)
-</p>
-<p class="indent" markdown="1">
-<i class="fas fa-file-pdf"></i>
 the internal documentation of the [tensor library](../assets/dynare++/tl.pdf)
 </p>
-<p class="indent" markdown="1">
-<i class="fas fa-file-pdf"></i>
-the internal documentation of the [k-order library](../assets/dynare++/kord.pdf)
-</p>