disable login button

[avsingh999]

disable login button when at least one input field is empty

Description

disable

Related Issue

#761

Motivation and Context

How Has This Been Tested?

Screenshots (In case of UI changes):

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[avsingh999]

@vivonk @agentmilindu Please review me. thank you : )