(various): document from_promisor parameter

88e2f9ed8e ("introduce fetch-object: fetch one promisor object",
2017-12-05) plumbed through the from_promisor parameter but did
not document it everywhere it appeared. Add the documentation.

(It also plumbed through the no_dependents parameter, but I have left
that alone because it is being removed in a commit under review [1].)

[1] https://lore.kernel.org/git/e8f16d69089a5011c355d5939c56fa53b7a1eb2d.1597184949.git.jonathantanmy@google.com/

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fetch-pack.h

@@ -40,6 +40,14 @@ struct fetch_pack_args {
 	unsigned cloning:1;
 	unsigned update_shallow:1;
 	unsigned deepen:1;
+
+	/*
+	 * Indicate that the remote of this request is a promisor remote. The
+	 * pack received does not need all referred-to objects to be present in
+	 * the local object store, and fetch-pack will store the pack received
+	 * together with a ".promisor" file indicating that the aforementioned
+	 * pack is a promisor pack.
+	 */
 	unsigned from_promisor:1;
 
 	/*

remote-curl.c

@@ -39,7 +39,10 @@ struct options {
 		/* One of the SEND_PACK_PUSH_CERT_* constants. */
 		push_cert : 2,
 		deepen_relative : 1,
+
+		/* see documentation of corresponding flag in fetch-pack.h */
 		from_promisor : 1,
+
 		no_dependents : 1,
 		atomic : 1,
 		object_format : 1;

transport.h

@@ -15,7 +15,10 @@ struct git_transport_options {
 	unsigned self_contained_and_connected : 1;
 	unsigned update_shallow : 1;
 	unsigned deepen_relative : 1;
+
+	/* see documentation of corresponding flag in fetch-pack.h */
 	unsigned from_promisor : 1;
+
 	unsigned no_dependents : 1;
 
 	/*