add link to WIP chapter 05 translation

Author: markburns

index.textile

@@ -7,7 +7,7 @@ h2. Table of contents
 Some chapters are previews. It means they have not been fully reviewed,
 some diagrams may be missing and some sentences may be a little
 rough. But it also means they are in open review, so do not hesitate
-to post suggestions on the mailing list.
+to address issues on the mailing list.
 
 * Preface
 * Introduction
@@ -19,6 +19,7 @@ h3. Part 1: Objects
 * "Chapter 3: Names and name tables":name.html
 * "Chapter 4: Classes and modules":class.html
 * "Chapter 5: Garbage collection":gc.html
+* "Chapter 5: Garbage collection - (unfinished alternative translation)":chapter05.html
 * "Chapter 6: Variables and constants":variable.html
 * "Chapter 7: Security":security.html