Custom Indicators Don't Use `.current.value`

[DerekMelchin]

Update tutorial on creating custom indicators to show how to enable .current.value usage, so they match the built-in indicators.
https://discordapp.com/channels/846109296973840424/846131651201466429/1435886437487738983

[anatoliykmetyuk]

For reference and example of expected vs current behavior, see: https://www.quantconnect.com/forum/discussion/19795/python-pythonindicator-current-property-undocumented-and-non-functional/p1

[AlexCatarino]

Closed by 1001f00.