feat: extend documentation for "improve", make example self-contained (#60)

* add introduction to tranlate function

* add introduction to "improve-function" documentation

* extend "improve function" docs

* fix typo

* revert changes to translate docs

* make example self-contained

Author: katharinaernst

docs/source/improve.rst

@@ -3,6 +3,10 @@
 Improve
 ==========================================================
 
+The improve functionality of search-query depicts the query refinement step of a literature search.
+This includes modification of the query.
+The search space can be expanded to include plural forms and spelling variants by including wildcard operators and nested OR queries, as shown in the following examples.
+
 Modification
 ---------------------
 

docs/source/save.rst

@@ -8,6 +8,9 @@ To write a query to a JSON file, run the serializer:
 .. code-block:: python
 
     from search_query import SearchFile
+    from search_query.and_query import AndQuery
+
+    query = AndQuery(["digital", "work"], field="title")
 
     search_file = SearchFile(
         filename="search-file.json",