chore: import upstream snapshot with attribution

docs/table-introspect-api.md

@@ -0,0 +1,32 @@
+# Table introspect API
+
+## Get table information
+
+```ts
+import { pgTable, getTableConfig } from 'drizzle-orm/pg-core';
+
+const table = pgTable(...);
+
+const {
+  columns,
+  indexes,
+  foreignKeys,
+  checks,
+  primaryKeys,
+  name,
+  schema,
+} = getTableConfig(table);
+```
+
+## Get table columns map
+
+```ts
+import { pgTable, getTableColumns } from 'drizzle-orm/pg-core';
+
+const table = pgTable('table', {
+  id: integer('id').primaryKey(),
+  name: text('name'),
+});
+
+const columns/*: { id: ..., name: ... } */ = getTableColumns(table);
+```