[RF] Fix link to file moved on GitHub

Closes root-project#15370.

File was moved in 6bb813f.

roofit/hs3/src/RooJSONFactoryWSTool.cxx

@@ -1109,7 +1109,7 @@ void RooJSONFactoryWSTool::exportObject(RooAbsArg const &func, std::set<std::str
                 << " 3: you are reading a file with export keys - call RooFit::JSONIO::printExportKeys() to "
                    "see what is available\n"
                 << " 2 & 1: you might need to write a serialization definition yourself. check "
-                   "https://github.com/root-project/root/blob/master/roofit/hs3/README.md to "
+                   "https://root.cern/doc/master/group__roofit__dev__docs__hs3.html to "
                    "see how to do this!\n";
       return;
    }
@@ -1243,7 +1243,7 @@ void RooJSONFactoryWSTool::importFunction(const JSONNode &p, bool importAllDepen
                "RooFit::JSONIO::printFactoryExpressions() "
                "to see what is available\n"
             << " 2 & 1: you might need to write a deserialization definition yourself. check "
-               "https://github.com/root-project/root/blob/master/roofit/hs3/README.md to see "
+               "https://root.cern/doc/master/group__roofit__dev__docs__hs3.html to see "
                "how to do this!"
             << std::endl;
          RooJSONFactoryWSTool::error(ss.str());

roofit/roofitmore/src/RooHypatia2.cxx

@@ -77,7 +77,7 @@
  * make it concave, and re-enable the tails. Especially \f$ \beta \f$ needs to be close to zero.
  *
  * ## Relation to RooIpatia2
- * This implementation is largely based on RooIpatia2, https://gitlab.cern.ch/lhcb/Urania/blob/master/PhysFit/P2VV/src/RooIpatia2.cxx,
+ * This implementation is largely based on RooIpatia2, https://gitlab.cern.ch/lhcb/Urania/-/blob/master/PhysFit/B2DXFitters/src/RooIpatia2.cxx,
  * but there are differences:
  * - At construction time, the Hypatia implementation checks if the range of parameters extends into regions where
  *   the function might be undefined.