Update history.

doc/math.qbk

@@ -9,7 +9,7 @@
     ]
     [authors [Agrawal, Nikhar], [Bikineev, Anton], [Borland, Matthew], [Bristow, Paul A.], [Holin, Hubert], [Guazzone, Marco], [Kormanyos, Christopher], [Lalande, Bruno], [Maddock, John], [Miller, Evan], [Murphy, Jeremy W.], [Pulver, Matthew], [Råde, Johan], [Sobotta, Benjamin], [Sewani, Gautam], [Thompson, Nicholas], [van den Berg, Thijs], [Walker, Daryle], [Zhang, Xiaogang]]
     [/last-revision $Date$]
-    [version 4.2.0]
+    [version 4.2.1]
 ]
 
 [template mathpart[id title]

doc/overview/roadmap.qbk

@@ -8,6 +8,16 @@ All old bug reports including closed ones can be viewed on Trac
 
 Recent issues on GitHub [@https://github.com/boostorg/math/issues?utf8=%E2%9C%93&q=is%3Aissue here].
 
+[h4 Math-4.2.1 (Boost-1.86)]
+
+* Correct Bessel function results at infinity, see [@https://github.com/boostorg/math/issues/1143 1143].
+* Improve Non Central T numerical stability, see [@https://github.com/scipy/scipy/issues/20693 scipy20693].
+* Correct `float_next`/`float_prior` behaviour at infinity.
+* Prevent spurious underflow in non-central beta, see [@https://github.com/scipy/scipy/issues/20693 scipy20693].
+* Add improvement to Heuman Lambda precision.
+* Improve Skew Normal root finding, see [@https://github.com/boostorg/math/issues/1120 1120].
+* Lots of minor fixes and improved code coverage.
+
 [h4 Math-4.2.0 (Boost-1.85)]
 
 * Add support for [link math_toolkit.jso  Single objective real-parameter optimization: Algorithm jSO].