Create projects.yml for safety critical OSS landscape

Adding a first non functional landscape file as base for later CNCF landscape drawing. 
The style is following: https://github.com/lf-energy/lfenergy-landscape/blob/main/landscape.yml

Author: pahmann

Documentation/landscape/projects.yml

@@ -0,0 +1,35 @@
+landscape:
+  - category:
+    name: Tools
+    subcategories:
+      - subcategory:
+        name: Compiler
+        items:
+          - item:
+            name: LLVM 
+            description: 
+            homepage_url: https://llvm.org/
+            repo_url: https://github.com/llvm
+            logo: 
+      - subcategory:
+        name: Requirements
+        items: []
+      - subcategory:
+        name: Static analysis
+        items: []
+      - subcategory:
+        name: Build tooling
+        items: []
+  - category:
+    name: Operating Systems
+      - subcategory:
+        name: Realtime
+        items: []
+  - category:
+    name: Frameworks
+      - subcategory:
+        name: Middleware
+        items: []
+    
+
+