Update blank-issue.md

[lasryariel]

added Feature: Missing and Complexity: Missing to default labels

Closes #replace_this_text_with_the_issue_number

What changes did you make?

• Added labels from the missing series

Rationale behind the changes?

• If the issues start off with the missing labels, the author will be more likely to add those labels on the issue when writing it.

Testing done for these changes

• Checked for Completeness and Capitalization

What did you learn or can share that is new?(optional)

Screenshots of Proposed Changes Of The Website (if any, please do not screen shot code changes)

Visuals before changes are applied

Visuals after changes are applied

[ExperimentsInHonesty]

The changes look good.

I checked for Capitalization and completeness.

[ExperimentsInHonesty]

@lasryariel I am closing this PR. But an additional change needs to be made to update the text reminder from

**UPDATE LABELS: Add the following labels to each new issue, and remove defaults:**
* Role
* Feature
* Points 
* Milestone

to

**UPDATE LABELS: Add the following labels to each new issue, and remove defaults:**
* Role
* Feature
* Points 
* Milestone
* Complexity