[documentation] tables: mention that table names can contain only letters, numbers and underscores
Created originally on Bitbucket by michel_samia (Michel Samia)
Everything else causes an error when opening in excel (however “repair” button will replace them by underscores)
This file https://bitbucket.org/openpyxl/openpyxl/src/ca7b1baf75f2/doc/worksheet_tables.rst?mode=view