Update version history to reflect API changes

Change-Id: I5ce744d72b991abba17b5cf9c6a1e1f158693151

docs/source/version_history.rst

diff --git a/docs/source/version_history.rst b/docs/source/version_history.rst
index 5acdb20..bddbbd7 100644
--- a/docs/source/version_history.rst
+++ b/docs/source/version_history.rst
@@ -7,6 +7,12 @@
 1.7.0
 =====
 
+Backward Incompatible API Changes
+---------------------------------
+
+#. ``Solver::Options::sparse_linear_algebra_library`` has been renamed
+   to ``Solver::Options::sparse_linear_algebra_library_type``.
+
 New Features
 ------------