Hessian Q in running text of README.md should be $; updated documentation of Highs_postsolve in the C API

Author: jajhall

README.md

@@ -46,7 +46,7 @@ linear optimization problems of the form
 
 $$ \min \quad \dfrac{1}{2}x^TQx + c^Tx \qquad \textrm{s.t.}~ \quad L \leq Ax \leq U; \quad l \leq x \leq u $$
 
-where Q must be positive semi-definite and, if Q is zero, there may be a requirement that some of the variables take integer values. Thus HiGHS can solve linear programming (LP) problems, convex quadratic programming (QP) problems, and mixed integer programming (MIP) problems. It is mainly written in C++, but also has some C. It has been developed and tested on various Linux, MacOS and Windows installations. No third-party dependencies are required.
+where $Q$ must be positive semi-definite and, if $Q$ is zero, there may be a requirement that some of the variables take integer values. Thus HiGHS can solve linear programming (LP) problems, convex quadratic programming (QP) problems, and mixed integer programming (MIP) problems. It is mainly written in C++, but also has some C. It has been developed and tested on various Linux, MacOS and Windows installations. No third-party dependencies are required.
 
 HiGHS has primal and dual revised simplex solvers, originally written by Qi Huangfu and further developed by Julian Hall. It also has an interior point solver for LP written by Lukas Schork, an active set solver for QP written by Michael Feldmeier, and a MIP solver written by Leona Gottwald. Other features have been added by Julian Hall and Ivet Galabova, who manages the software engineering of HiGHS and interfaces to C, C#, FORTRAN, Julia and Python.
 

highs/interfaces/highs_c_api.h

@@ -400,7 +400,9 @@ HighsInt Highs_presolve(void* highs);
 HighsInt Highs_run(void* highs);
 
 /**
- * Postsolve a model using a primal (and possibly dual) solution.
+ * Postsolve a model using a primal (and possibly dual) solution. The
+ * postsolved solution can be retrieved later by calling
+ * `Highs_getSolution`.
  *
  * @param highs       A pointer to the Highs instance.
  * @param col_value   An array of length [num_col] with the column solution
@@ -413,7 +415,8 @@ HighsInt Highs_run(void* highs);
  * @returns A `kHighsStatus` constant indicating whether the call succeeded.
  */
 HighsInt Highs_postsolve(void* highs, const double* col_value,
-                         const double* col_dual, const double* row_dual);
+                         const double* col_dual,
+			 const double* row_dual);
 
 /**
  * Write the solution information (including dual and basis status, if