commit-graph: introduce 'commitGraph.maxNewFilters'

Introduce a configuration variable to specify a default value for the
recently-introduce '--max-new-filters' option of 'git commit-graph
write'.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/config/commitgraph.txt b/Documentation/config/commitgraph.txt
index cff0797..4582c39 100644
--- a/Documentation/config/commitgraph.txt
+++ b/Documentation/config/commitgraph.txt
@@ -1,3 +1,7 @@
+commitGraph.maxNewFilters::
+	Specifies the default value for the `--max-new-filters` option of `git
+	commit-graph write` (c.f., linkgit:git-commit-graph[1]).
+
 commitGraph.readChangedPaths::
 	If true, then git will use the changed-path Bloom filters in the
 	commit-graph file (if it exists, and they are present). Defaults to
diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
index 8c75855..de6b6de 100644
--- a/Documentation/git-commit-graph.txt
+++ b/Documentation/git-commit-graph.txt
@@ -71,7 +71,8 @@
 filters (if `--changed-paths` is specified). If `n` is `-1`, no limit is
 enforced. Only commits present in the new layer count against this
 limit. To retroactively compute Bloom filters over earlier layers, it is
-advised to use `--split=replace`.
+advised to use `--split=replace`.  Overrides the `commitGraph.maxNewFilters`
+configuration.
 +
 With the `--split[=<strategy>]` option, write the commit-graph as a
 chain of multiple commit-graph files stored in