Add new transaction types

[fabrice102]

Is your addition related to a problem? Please describe.

The page https://developer.algorand.org/docs/features/transactions/#transaction-types is missing the application call transaction type.

Describe the solution you'd like

Add the application call transaction type.
It may also be helpful to add a link to https://developer.algorand.org/docs/reference/transactions/ that contains the application call transaction type.

[barnjamin]

Good point, working on this now