Update README.md

SFEM/README.md

@@ -60,7 +60,7 @@ Instructions for Debian/Ubuntu based workstations are as follows.
      * ```meanX = np.array([0.5,10])```    # mean of variables
      * ```stdX = np.array([0.05,0.1])```       # std of variables
      * ```rho = 0.2```
-     * ```R0_XY = np.array([[1, rho], [rho, 1]])```  #covariance matrix
+     * ```R0_XY = np.array([[1, rho], [rho, 1]])```  #correlation matrix
   * And from a the correlation lengths along the 3 direction
      * ```lc = [15., 15., 15.]```            # correlation length
   * The number of RFs to be generated follows from