[gimp] devel-docs: update a reference to 32-bit pointers.

[Jehan <jehanp src gnome org>]

commit 35f55ef07a39e3358e9cb3a1a8922f5b09689e2d
Author: Jehan <jehan girinstud io>
Date:   Wed Oct 2 01:08:17 2019 +0200

    devel-docs: update a reference to 32-bit pointers.
    
    Though the description of the POINTER type clearly tells of the new type
    size, it was still refered as 32-bit only in this introductory text.
    Let's fix this.

 devel-docs/xcf.txt | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/devel-docs/xcf.txt b/devel-docs/xcf.txt
index 2c394f93e6..623d5d3854 100644
--- a/devel-docs/xcf.txt
+++ b/devel-docs/xcf.txt
@@ -197,11 +197,14 @@ the very beginning of the file, and that the tile data blocks for each drawable
 must follow each other directly.
 
 References _between_ structures in the XCF file take the form of
-32-bit "pointers" that count the number of bytes between the beginning of
-the XCF file and the beginning of the target structure. Note that therefore
-the maximum address of a layer, channel, hierarchy or tile set is 2^32 - 1,
-i.e. at 4 GB. Everything after will be lost. Currently this doesn't play a
-role yet.
+"pointers" that count the number of bytes between the beginning
+of the XCF file and the beginning of the target structure.
+Pointers used to be 32-bit data. Since the maximum address of a layer,
+channel, hierarchy or tile set was 2^32 - 1, i.e. at 4 GB, the maximum
+size for XCF images before GIMP 2.10.0 was quite limited.
+Now pointers can be 64-bit, allowing files big enough for any image
+produced by current technology. See the chapter "Basic data types" for
+description of the POINTER type.
 
 Each structure is designed to be written and read sequentially; many
 contain items of variable length and the concept of an offset _within_