Create Developers top level menu

This introduces a new top-level "Developers" menu. It takes the following from the Athena menu:

- all of the material in the "Athena developers" sub-menu of Athena
- the Git workflow (including the Git tutorial underneath it)
- IDE integration

Other menus are left alone, with the exception that the "Software infrastructure" menu is renamed "Shifts and infrastructure".

Other changes:

- the ordering of the items in the developers' menu is slightly changed
- the persistency section of the developers' tutorial is moved to its correct place
- an evidently orphaned part of the Git tutorial is reunited with the rest of the material (see #47)

mkdocs.yml

@@ -66,15 +66,62 @@ nav:
         - athena/configuration/tutorial/fragments.md
         - athena/configuration/tutorial/tools.md
         - athena/configuration/tutorial/steering.md
-    - Athena developers:
+    - Containers and VMs:
+      - athena/containers/index.md
+      - athena/containers/intro-docker.md
+      - athena/containers/mac-setup.md
+      - athena/containers/ubuntu-setup.md
+      - athena/containers/dev-setup.md
+      - athena/containers/lima.md
+    - Performance and monitoring:
+      - athena/performance/index.md
+      - Monitoring:
+        - athena/performance/perfmonmt.md
+        - athena/performance/prmon.md
+      - Performance:
+        - athena/performance/valgrind.md
+        - athena/performance/valgrind-examples.md
+        - athena/performance/heaptrack.md
+        - athena/performance/callgrind.md
+        - athena/performance/vtune.md
+    - athena/gpu/index.md
+    - athena/io/index.md
+  - Developers:
       - athena/developers/index.md
       - athena/developers/releases.md
+      - Git workflow:
+        - athena/git/index.md
+        - athena/git/workflow-quick.md
+        - athena/git/continuous-integration.md
+        - athena/git/resolve-conflict.md
+        - athena/git/git-atlas.md
+        - athena/git/tips.md
+        - Git tutorial:
+          - athena/git/env-setup.md
+          - athena/git/gitlab-fork.md
+          - athena/git/clone.md
+          - athena/git/branch.md
+          - athena/git/develop.md
+          - athena/git/commit.md
+          - athena/git/merge-request.md
+        - Archived:
+          - athena/git/pseudomerge.md
+          - athena/git/svn-migrate.md
+      - IDE integration & VSCode:
+        - athena/ide/index.md
+        - IDE Integrations:
+          - athena/ide/setup.md
+          - athena/ide/cpp.md
+          - athena/ide/python.md
+        - VS Code Usage Patterns:
+          - athena/ide/native.md
+          - athena/ide/ssh.md
+          - athena/ide/docker.md
       - athena/developers/cmake.md
       - athena/developers/building.md
       - athena/developers/building-externals.md
       - athena/developers/calib.md
       - athena/developers/issue-reporting.md
-      - athena/git/develop.md
       - coding-guidelines/index.md
       - Developer tutorial:
         - athena/developers/tutorial/index.md
@@ -85,58 +132,11 @@ nav:
         - athena/developers/tutorial/vscode.md
         - athena/developers/tutorial/cpp.md
         - athena/developers/tutorial/writing-algstools.md
+        - athena/developers/tutorial/persistency.md
         - athena/developers/tutorial/cmake.md
         - athena/developers/tutorial/testing_debugging.md
         - athena/developers/tutorial/conditions.md
         - athena/developers/tutorial/performance.md
-        - athena/developers/tutorial/persistency.md
-    - Git Workflow:
-      - athena/git/index.md
-      - athena/git/workflow-quick.md
-      - athena/git/continuous-integration.md
-      - athena/git/resolve-conflict.md
-      - athena/git/git-atlas.md
-      - athena/git/tips.md
-      - Git Tutorial:
-        - athena/git/env-setup.md
-        - athena/git/gitlab-fork.md
-        - athena/git/clone.md
-        - athena/git/branch.md
-        - athena/git/commit.md
-        - athena/git/merge-request.md
-      - Archived:
-          - athena/git/pseudomerge.md
-          - athena/git/svn-migrate.md
-    - IDE integration & VSCode:
-      - athena/ide/index.md
-      - IDE Integrations:
-        - athena/ide/setup.md
-        - athena/ide/cpp.md
-        - athena/ide/python.md
-      - VS Code Usage Patterns:
-        - athena/ide/native.md
-        - athena/ide/ssh.md
-        - athena/ide/docker.md
-    - Containers and VMs:
-      - athena/containers/index.md
-      - athena/containers/intro-docker.md
-      - athena/containers/mac-setup.md
-      - athena/containers/ubuntu-setup.md
-      - athena/containers/dev-setup.md
-      - athena/containers/lima.md
-    - Performance and monitoring:
-      - athena/performance/index.md
-      - Monitoring:
-        - athena/performance/perfmonmt.md
-        - athena/performance/prmon.md
-      - Performance:
-        - athena/performance/valgrind.md
-        - athena/performance/valgrind-examples.md
-        - athena/performance/heaptrack.md
-        - athena/performance/callgrind.md
-        - athena/performance/vtune.md
-    - athena/gpu/index.md
-    - athena/io/index.md
   - Trigger:
     - Trigger Developers Guide:
       - athena/trigger/index.md
@@ -165,7 +165,7 @@ nav:
       - athena/trigger/menumonitoring.md
       - athena/trigger/menutriggerapi.md
       - athena/trigger/triggerdb.md
-  - Software infrastructure:
+  - Shifts and infrastructure:
     - software-infrastructure/index.md
     - software-infrastructure/code-review/index.md
     - Merge Review Shifts Tutorial: