refactor(docs): rename dependency group to docs

The dependency group for documentation has been renamed to docs [1],
rename it to align with this change.

[1] https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/30344

Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
Change-Id: Ia29170b4416aa9a3466444f129d453872a5e482b
diff --git a/group/tf-l1-check-docs/build-docs:nil b/group/tf-l1-check-docs/build-docs:nil
index 5389df0..9cfc8e8 100644
--- a/group/tf-l1-check-docs/build-docs:nil
+++ b/group/tf-l1-check-docs/build-docs:nil
@@ -6,7 +6,7 @@
 #
 
 pre_tf_build() {
-	poetry -C "$tf_root" install --with doc
+	poetry -C "$tf_root" install --with docs
 	targets="doc" set_tf_build_targets
 }