remove dup info, add info to nav

Author: sshanks-kx

docs/basics/memory-backed.md

@@ -392,11 +392,11 @@ nav:
         - if: ref/if.md
         - while: ref/while.md
       - Namespaces:
-        - .h: ref/doth.md
-        - .j: ref/dotj.md
-        - .m: ref/dotm.md
-        - .Q: ref/dotq.md
-        - .z: ref/dotz.md
+        - .h (markup): ref/doth.md
+        - .j (JSON): ref/dotj.md
+        - .m (memory backed files): ref/dotm.md
+        - .Q (utils): ref/dotq.md
+        - .z (env, callbacks): ref/dotz.md
       - Application: basics/application.md
       - Atomic functions: basics/atomic.md
       - Comparison: basics/comparison.md
@@ -414,7 +414,6 @@ nav:
       - Internal functions: basics/internal.md
       - Joins: basics/joins.md
       - Mathematics: basics/math.md
-      - Memory backed by files: basics/memory-backed.md
       - Metadata: basics/metadata.md
       - Namespaces: basics/namespaces.md
       - Parse trees: basics/parsetrees.md