define mdfiles/images in config/submodules/docs/

again: the "depend" variable must never be used for subprojects
that point to a subdirectory of the main project, because there's
no clean way of handling this in case of error conditions.

make it a submodule under config/submodules/. this is for the
documentation, including static site generator documentation,
and image files (photos).

as of this revision, there are now only those "depend" projects
defined in config/git/, where the destination directory of the
subject is not a subdirectory of the main project, so:

in a subsequest revision, i will mitigate an existing bug whereby
failure of the dependency project leaves the main one still
intact, breaking builds; this revision enables that to be done.

from now on, subproject-to-subdirectory-of-main-project will
be avoided in config/git/; config/submodules/ will be used.

Signed-off-by: Leah Rowe <leah@libreboot.org>

config/submodule/docs/html/module.cfg

@@ -0,0 +1,3 @@
+subrev="20fd775c855428ecff647a42823746863fd57efe"
+subrepo="https://codeberg.org/libreboot/lbwww"
+subrepo_bkup="https://git.disroot.org/libreboot/lbwww"

config/submodule/docs/img/module.cfg

@@ -0,0 +1,3 @@
+subrev="625bb7535d388a235bec47a8ce822cda10b53692"
+subrepo="https://codeberg.org/libreboot/lbwww-img"
+subrepo_bkup="https://git.disroot.org/libreboot/lbwww-img"

config/submodule/docs/module.list

@@ -0,0 +1,3 @@
+www/untitled
+www/html
+www/html/site/img

config/submodule/docs/untitled/module.cfg

@@ -0,0 +1,3 @@
+subrev="d8e2043c1512eb1171c274559ce82e8093ef393f"
+subrepo="https://codeberg.org/vimuser/untitled-website"
+subrepo_bkup="https://notabug.org/untitled/untitled-website"