Fix incorrect inequality in watts_strogatz documentation

[simonschoelly]

No description provided.

[aurorarossi]

I don't agree with this change.
In the code there is the following check:

(rand(rng) < β && degree(g, s) < n - 1) || continue

which means that if r=rand(rng) is less than β then the edge is rewired otherwise (if r bigger or equal to β) the edge is left unaltered.
Indeed, in the special cases:

• if β=0 then r is always bigger than 0 that leads to no change in the lattice.
• if β=1 then r is always less than 1 and the whole graph is rewired.