[PATCH v2] doc: core.ignoreStat update, and clarify the --assume-unchanged effect

[Philip Oakley <philipoakley@iee.org>]

The assume-unchanged bit, and consequently core.ignoreStat, can be
misunderstood. Be assertive about the expectation that file changes should
notified to Git.

Signed-off-by: Philip Oakley <philipoakley@iee.org>
---
Overhaul the general wording thus:
    1. direct description of what is ignored given first.
    2. example instruction of the user manual action required.
    3. use sideways indirection for assume-unchanged and update-index references.
    4. add a 'normally' to give leeway for the change detection.

This version is on top of the current master, and replaces the patch in next.
---
 Documentation/config.txt | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 6862e3e..32e42dd 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -375,13 +375,17 @@ This is useful for excluding servers inside a firewall from
 proxy use, while defaulting to a common proxy for external domains.
 
 core.ignoreStat::
-	If true, commands which modify both the working tree and the index
-	will mark the updated paths with the "assume unchanged" bit in the
-	index. These marked files are then assumed to stay unchanged in the
-	working tree, until you mark them otherwise manually - Git will not
-	detect the file changes	by lstat() calls. This is useful on systems
-	where those are very slow, such as Microsoft Windows.
-	See linkgit:git-update-index[1].
+	If true, Git will avoid using lstat() calls to detect if files have
+	changed. Git will set the "assume-unchanged" bit for those tracked files
+	which it has updated identically in both the index and working tree.
++
+	When files are modified outside of Git, the user will need to stage
+	the modified files explicitly (e.g. see 'Examples' section in
+	linkgit:git-update-index[1]).
+	Git will not normally detect changes to those files.
++
+	This is useful on systems where lstat() calls are very slow, such as
+	CIFS/Microsoft Windows.
 	False by default.
 
 core.preferSymlinkRefs::
-- 
1.9.5.msysgit.0