Add docs and tests for the simple cases lol

Signed-off-by: cobalt <61329810+RedGuy12@users.noreply.github.com>

docs/the_black_code_style/future_style.md

@@ -128,6 +128,11 @@ Parenthesises around sole list items will also be removed for similar reasons. T
 commas are respected here as well. For example:
 
 ```python
+items = [(123)]
+items = [(True)]
+items = [((True,))]
+items = [(())]
+
 items = [
     (
         long_variable_name
@@ -148,6 +153,11 @@ items = [
 will be changed to:
 
 ```python
+items = [123]
+items = [True]
+items = [(True,)]
+items = [()]
+
 items = [
     long_variable_name
     and even_longer_variable_name

tests/data/cases/preview_remove_sole_list_item_parens.py

@@ -1,4 +1,10 @@
 # flags: --unstable
+items = [(123)]
+items = [(True)]
+items = [(((((True)))))]
+items = [(((((True,)))))]
+items = [((((()))))]
+
 items = [
     (
         {"key1": "val1", "key2": "val2", "key3": "val3"}
@@ -84,6 +90,12 @@
 
 
 # output
+items = [123]
+items = [True]
+items = [True]
+items = [(True,)]
+items = [()]
+
 items = [
     {"key1": "val1", "key2": "val2", "key3": "val3"}
     if some_var == "longstring"