Update README.md

  indices of the rotation axis such as 1 0 0, 1 1 1, 1 1 0 and so on. The limit

  is the maximum Sigma of interest.

  (the limit by default: 100)_

  _ex:_

```

> python csl_generator.py 1 1 1 50 

...

  List of possible CSLs for [1 1 1] axis sorted by Sigma

Sigma:     1  Theta:   0.00

Sigma:     3  Theta:  60.00

Sigma:     7  Theta:  38.21

Sigma:    39  Theta:  32.20

Sigma:    43  Theta:  15.18

Sigma:    49  Theta:  43.57

```

Once you pick one of these angles (sigma boundaries) you should use the second mode, decide on a basis, for ex: diamond, and list the GB planes of interest:

```

> python csl_generator.py 1 1 1 diamond 13

----------List of possible CSL planes for Sigma 13---------

 GB1---------------GB2-------------Type----------Number of Atoms

[ 2  1 -2]             [ 1  2 -2]             Mixed                  3744

[-1 -1 -1]             [-1 -1 -1]             Twist                  1248

[1 1 1]                [1 1 1]                Twist                  1248

[-1  2 -2]             [-2  2 -1]             Mixed                  3744

[ 1 -2  2]             [ 2 -2  1]             Mixed                  3744

[-2 -1  2]             [-1 -2  2]             Mixed                  3744

[-3 -2  1]             [-2 -3  1]             Mixed                  2912

[ 0 -3  1]             [ 1 -3  0]             Mixed                  2080

[ 1  3 -4]             [-1  4 -3]             Symmetric Tilt         1248

  ...

```

Which you can write to a file if you wish.