Minor correction of formula in Route Blinding subsection: $e_0 /leftarrow {0;1}^256$ --> $e_0 \leftarrow {0;1}^{256}$

[dple]

No description provided.

[t-bast]

I'm seeing a few other issues that were missed in @Roasbeef's #1151 and should be fixed:

• line 502: most of the text is truncated
• line 508: E_{i+1} doesn't render correctly
• line 521: the backticks of "blinded_node_id" don't render correctly
• there are occurences of E_i and E_r in the Rationale section, which should be updated to $E_i$ and $E_r$?

[t-bast]

Closed in favor of #1158