docs/manual: document the new get-developers -e option

Explain how this can be used with git send-email, and how git can be
configured to use it automatically.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 507d56a6be67b7b4e5c40b55c2e56ffbb4ff0386)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

docs/manual/contribute.txt

@@ -304,6 +304,28 @@ Use the output of +get-developers+ to send your patches:
 $ git send-email --to buildroot@buildroot.org --cc bob --cc alice outgoing/*
 ---------------------
 
+Alternatively, +get-developers -e+ can be used directly with the
++--cc-cmd+ argument to +git send-email+ to automatically CC the
+affected developers:
+
+---------------------
+$ git send-email --to buildroot@buildroot.org \
+      --cc-cmd './utils/get-developers -e' origin/master
+---------------------
+
++git+ can be configured to automatically do this out of the box with:
+
+---------------------
+$ git config sendemail.to buildroot@buildroot.org
+$ git config sendemail.ccCmd "$(pwd)/utils/get-developers -e"
+---------------------
+
+And then just do:
+
+---------------------
+$ git send-email origin/master
+---------------------
+
 Note that +git+ should be configured to use your mail account.
 To configure +git+, see +man git-send-email+ or google it.
 

docs/manual/developers.txt

@@ -31,7 +31,8 @@ the +DEVELOPERS+ file for various tasks:
 
 - When passing one or several patches as command line argument,
   +get-developer+ will return the appropriate +git send-email+
-  command.
+  command. If the +-e+ option is passed, only the email addresses are
+  printed in a format suitable for +git send-email --cc-cmd+.
 
 - When using the +-a <arch>+ command line option, +get-developer+ will
   return the list of developers in charge of the given architecture.