Doc comment is not rendered correctly for Measure operation

[DmitryVasilevsky]

Playground doesn't render Measure doc comment correctly.
Also \boldone is not supported.

• Make sure that the doc comment for Measure operation is rendered correctly in the playground.
• Remove \boldone from doc comments.

As a result of discussion with @vadym-kl we arrived at the following formula

$\langle\psi| \frac{I + P_0 \otimes \ldots \otimes P_{N-1}}{2} |\psi\rangle$

We'll use it in the doc comment for the Measure operation. We'll also drop the non-standard notation for probability

$\Pr(\texttt{Zero} \mid \ket{\psi})$