Document constructor

Author: scheinerman

README.md

@@ -1,4 +1,26 @@
 # SimpleTableaux
 
 Illustration project for the optimization problem
-$\max c^t x$ subject to $Ax ≤ b$.
+$\max c^t x$ subject to $Ax ≤ b$.
+
+## Construction
+
+Start with these:
+```
+A = [3 5; 4 1]
+b = [78; 36]
+c = [5; 4]
+```
+Then set up the `Tableau` as follows:
+```
+julia> T = Tableau(A,b,c)
+3×6 DataFrame
+ Row │ x1     x2     s1     s2     val    RHS   
+     │ Exact  Exact  Exact  Exact  Exact  Exact 
+─────┼──────────────────────────────────────────
+   1 │ 3      5      1      0      0      78
+   2 │ 4      1      0      1      0      36
+   3 │ -5     -4     0      0      1      0
+```
+Notice that the last row is the encoding of the objective function.
+