[gegl] docs: fix a typo

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 6a7b2f1dd3f44aa09ea6d44ecc651eea60ffa4db
Author: Øyvind Kolås <pippin gimp org>
Date:   Sat May 23 20:01:44 2020 +0200

    docs: fix a typo

 docs/environment.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/docs/environment.txt b/docs/environment.txt
index 0852c1515..188d02345 100644
--- a/docs/environment.txt
+++ b/docs/environment.txt
@@ -11,7 +11,7 @@ BABL_TOLERANCE::
     The amount of error that babl tolerates, set it to for instance 0.1 to use
     some conversions that trade some quality for speed.
 GEGL_CHUNK_SIZE::
-    The number of pixels processed simulatnously.
+    The number of pixels processed simultanously.
 GEGL_TILE_SIZE::
     The tile size used internally by GEGL, defaults to 128x64
 GEGL_SWAP::