Python Examples - Updating Operations.md

[tebanieo]

This is a summary of the work that needs to be completed on this issue:

• Fix DeleteItemConditional reference to point to delete_item_conditional.py.
• Add, pagination.py, query-scan-count.py, query_begins_with.py and query_equals.py to the Operations.md file.
• Identify the examples that matches the WorkingWithIndexes description, the examples might also be present under a different category.
• Add entry for add_gsi.py and enable_continuous_backups.py.
• Renaming table_change_to_on-demand.py and table_change_to_provisioned.py to update_table_on-demand and update_table_provisioned so it's consistent with what's in Operations.MD
• Add entry for paginated-query-batch-execute-statement.py and paginated-select-statement.py
• Add entry for WorkingWithCustomBackoffRetry exists but is not documented in README
• Update Count in the table to match query-scan-count.py.

Originally posted by @tebanieo in #124 (comment)

[davetownG]

I would like to work on this issue, but am unable to assign to myself.