Clarify column types in create-table help

docs/cli-reference.rst

@@ -886,6 +886,8 @@ See :ref:`cli_create_table`.
               height float \
               photo blob --pk id
 
+      Valid column types are text, integer, float and blob.
+
     Options:
       --pk TEXT                 Column to use as primary key
       --not-null TEXT           Columns that should be created as NOT NULL

sqlite_utils/cli.py

@@ -1477,6 +1477,8 @@ def create_table(
             name text \\
             height float \\
             photo blob --pk id
+
+    Valid column types are text, integer, float and blob.
     """
     db = sqlite_utils.Database(path)
     _load_extensions(db, load_extension)