doc: add book section on misc. ops on treeseqs

book/src/SUMMARY.md

@@ -13,3 +13,4 @@
   - [Initialization from a table collection](./tree_sequence_from_table_collection.md)
   - [Iterating over trees](./tree_sequence_iterate_trees.md)
   - [Working with trees](./tree_sequence_tree.md)
+  - [Miscellaneous operations](./tree_sequence_miscellaneous.md)

book/src/tree_sequence_miscellaneous.md

@@ -0,0 +1,37 @@
+## Miscellaneous operations
+
+### Writing to a file
+
+```rust, noplayground, ignore
+treeseq.dump("file.trees", tskit::TableOutputOptions::default()).unwrap();
+```
+
+### Loading from a file
+
+```rust, noplayground, ignore
+let treeseq = tskit::TreeSequence::load("file.trees").unwrap();
+```
+
+### Get a deep copy of the tables
+
+Get a *copy* of the table collection in the tree sequence:
+
+```rust, noplayground, ignore
+let tables = treeseq.dump_tables.unwrap();
+```
+
+This function can error because the `tskit-c` functions to copy ,may return an error code.
+
+This function is not necessary to access the tables.
+See below.
+
+### Read-only table access
+
+A `TreeSequence` has a `Deref` target giving read-only access to the tables:
+
+```rust, noplayground, ignore
+for _edge in treeseq.edges_iter() {
+}
+```
+
+