commit-graph: remove Future Work section

The commit-graph feature began with a long list of planned
benefits, most of which are now complete. The future work
section has only a few items left.

As for making more algorithms aware of generation numbers,
some are only waiting for generation number v2 to ensure the
performance matches the existing behavior using commit date.

It is unlikely that we will ever send a commit-graph file
as part of the protocol, since we would need to verify the
data, and that is expensive. If we want to start trusting
remote content, then that item can be investigated again.

While there is more work to be done on the feature, having
a section of the docs devoted to a TODO list is wasteful and
hard to keep up-to-date.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/technical/commit-graph.txt

@@ -127,23 +127,6 @@ Design Details
   helpful for these clones, anyway. The commit-graph will not be read or
   written when shallow commits are present.
 
-Future Work
------------
-
-- After computing and storing generation numbers, we must make graph
-  walks aware of generation numbers to gain the performance benefits they
-  enable. This will mostly be accomplished by swapping a commit-date-ordered
-  priority queue with one ordered by generation number. The following
-  operations are important candidates:
-
-    - 'log --topo-order'
-    - 'tag --merged'
-
-- A server could provide a commit-graph file as part of the network protocol
-  to avoid extra calculations by clients. This feature is only of benefit if
-  the user is willing to trust the file, because verifying the file is correct
-  is as hard as computing it from scratch.
-
 Related Links
 -------------
 [0] https://bugs.chromium.org/p/git/issues/detail?id=8