bug#61726: [PATCH] Eglot: Support positionEncoding capability

[Eli Zaretskii]

> From: João Távora <joaotavora@gmail.com>
> Date: Sun, 26 Feb 2023 13:13:16 +0000
> Cc: Augusto Stoffel <arstoffel@gmail.com>, 61726@debbugs.gnu.org
> 
> * Pushed a renaming/redocumenting obsoletion-establishing patch.  Now
> Eglot talks of "linepos" instead of "column".

I've corrected a few doc strings to use a more widely-familiar
terminology.