Add inception baseline and milestone plan for Higher Lower

Add the Business Case, Stakeholder Analysis and Project Plan, and four
milestones (MIL-001 Project setup, MIL-002 Game logic, MIL-003 Console
game, MIL-004 Documentation and release) with Go/No-Go criteria and
task tables.

Set the PO language to en in the artifact registry. Link the synced
Gitea Milestones (36-39) in the Project Plan. The 20 task rows were
synced as issues #1-#20.

Refs #5

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "framework"]
+	path = framework
+	url = ssh://git@git.tirsystem.com:10022/TirSystem/SQA-QC-Framework.git