Correcting the error in getnetworkhashrateps

In the correction of an earlier mistake regarding the variance of the bandwidth ($bw$) estimator, it was clarified that the standard deviation is more accurately represented as $\frac{n}{\sqrt{k-2}}$, diverging from the previously thought $\frac{n}{\sqrt{k-1}}$. This adjustment has implications for the application of a specific algorithm designed to estimate the amount of work within a given window of blockchain blocks. The methodology for this estimation involves several steps beginning with identifying the lowest target ($T$) across all blocks under consideration. Following this, one must compile a set ($S$) of block hashes that are not only below $T$ but may also come from blocks with varying targets than $T$. Among these collected hashes, the highest hash ($H$), which is closest to the target $T$, is singled out. The final step in the work estimation process utilizes the formula $(S -1) \times \frac{2^{256}}{H}$, where $S$ represents the total number of hashes in the set, and $H$ is the highest hash value. This formula offers a systematic approach to quantifying the work done over a specified range of blocks within blockchain operations.