Fix doc typos in binary discrete optimizer module (pyswarms.discrete.…

…binary) (#409)

* Fix typo in formula: 'm' --> 'w'

Since 'm' wasn't defined anywhere, I assumed the inertia 'w' was actually meant here, similar to the formula for the real-valued algorithm

* Add missing 'w' entry in `options` dict keyword argument in doc for BinaryPSO init

The 'w' key was missing in the `options` dictionary, but was described below in the list (and is used in the code as well).

pyswarms/discrete/binary.py

@@ -14,7 +14,7 @@
 
 .. math::
 
-   v_{ij}(t + 1) = m * v_{ij}(t) + c_{1}r_{1j}(t)[y_{ij}(t) − x_{ij}(t)] + c_{2}r_{2j}(t)[\hat{y}_{j}(t) − x_{ij}(t)]
+   v_{ij}(t + 1) = w * v_{ij}(t) + c_{1}r_{1j}(t)[y_{ij}(t) − x_{ij}(t)] + c_{2}r_{2j}(t)[\hat{y}_{j}(t) − x_{ij}(t)]
 
 For the velocity update rule, a particle compares its current position
 with respect to its neighbours. The nearest neighbours are being
@@ -87,7 +87,7 @@ def __init__(
             number of particles in the swarm.
         dimensions : int
             number of dimensions in the space.
-        options : dict with keys :code:`{'c1', 'c2', 'k', 'p'}`
+        options : dict with keys :code:`{'c1', 'c2', 'w', 'k', 'p'}`
             a dictionary containing the parameters for the specific
             optimization technique
                 * c1 : float