At least one of the patches for the original release replaces the installation's 25k readme.txt (table of contents below) with the change log you see in the GOG release readme.txt. There's some useful information in section 2, so I recommend GOG add this file to their release. It can be found on Disk 1, and I've uploaded it here:
https://dl.dropboxusercontent.com/u/51613210/readme.txt

REVENANT

README.TXT File
(C) 1999 Eidos Interactive
10-11-1999

Contents

[1.0] Welcome
[1.1] System Requirements
[1.2] Memory Recommendations
[1.3] Installation
[2.0] Getting Around
[2.1] Running/Walking
[2.2] Town Teleports
[2.3] Picking up items
[2.4] Getting Stuck
[3.0] Manual Changes
[4.0] Options Changes
[5.0] Multi-player
[6.0] Video Card compatability
[6.1] Video cards which require updated drivers
[6.2] Known video card compatibility issues
[6.3] Running the game in Software Mode
[6.4] Advanced Options
[7.0] Customer Support
[8.0] Options