Merge pull request #5 from Pytlicek/update_readme

Update README.md with more accurate language.

Author: bai-yi-bai

Diff for: README.md

@@ -19,7 +19,7 @@ This library has 2 main features: reading a spreadsheet files and converting the
 ### - XLSX
 Use `xlsx_to_dict()` method  when converting form spreadsheets.  
 Supported file formats for spreadsheets are: .xlsx,.xlsm,.xltx,.xltm  
-Spreadsheets with multiple worksheets are supported. If no sheet is specified, the first sheet is selected.
+Spreadsheets with multiple worksheets are supported. If no sheet is specified, the active sheet is selected. If there is only one sheet, it is considered active.
 
 ```python3
 # Import the library
@@ -28,6 +28,9 @@ from sheet2dict import Worksheet
 # Create an object
 ws = Worksheet()
 
+# Convert active sheet (without specifying sheet name)
+ws.xlsx_to_dict(path='inventory.xlsx')
+
 # Convert the 'Main Warehouse' sheet of the 'inventory.xslx' spreadsheet file.
 ws.xlsx_to_dict(path='inventory.xlsx', select_sheet='Main Warehouse')