Fix documentation of the default value for core.streamFileThreshold

Since commit bfe9eec1 the default value for core.streamFileThreshold
is 25% of the available JVM heap, limited to 2048m.

Change-Id: I9308875e30470dc33bf9b437909842e87f974141
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index dee7fd2..d05db32 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -1065,8 +1065,7 @@
 when handling very big binary files, such as device firmware or
 CD-ROM ISO images.
 +
-Default is 50 MiB on all platforms.  Prior to Gerrit 2.1.6,
-this value was effectively 2047 MiB.
+Defaults to 25% of the available JVM heap, limited to 2048m.
 +
 Common unit suffixes of 'k', 'm', or 'g' are supported.