Broken markdown in Math page

[navistonks]

A paragraph under the Routing Payment section of the Mathematical Proofs has broken markdown ( relevant section in bold ):

But, the attacker is only getting the honest fees back, so for a single golden ticket solution the payout is the portion of fees that go to the routing reward $f\cdotPs& minus the fees the attacker put into the block $f\cdot p$

While it should look like this:

But, the attacker is only getting the honest fees back, so for a single golden ticket solution the payout is the portion of fees that go to the routing reward $f\cdot Ps\cdot p$ minus the fees the attacker put into the block $f\cdot p$

This PR fixes it: #4