Add Azure Blob Storage Delete operation doc

[fabistb]

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Description

Adds documentation for the delete operation of the Azure Blob binding.

Issue reference

#1277

[ghost]

All CLA requirements met.

[AaronCrawfis]

Since this functionality won't be released until Dapr v1.2, please retarget PR to the v1.2 branch

[fabistb]

Since this functionality won't be released until Dapr v1.2, please retarget PR to the v1.2 branch

Unfortunately it slipped through creating the necessary docs PR.
The functionality should already be available in version 1.1.0.

https://github.com/dapr/dapr/releases/tag/v1.1.0
dapr/components-contrib#681

[AaronCrawfis]

Since this functionality won't be released until Dapr v1.2, please retarget PR to the v1.2 branch

Unfortunately it slipped through creating the necessary docs PR.
The functionality should already be available in version 1.1.0.

https://github.com/dapr/dapr/releases/tag/v1.1.0
dapr/components-contrib#681

Sounds good, thanks for the clarification!