Added alt texts

[dbeezt]

Fixes

Checklist

• [X] I have made a material change to the repo (functionality, testing, spelling, grammar)
• [X] I have read the [Contribution Guide] and my PR follows them.
• [X] I updated my branch with the master branch.
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation about the functionality in the appropriate .md file
• [ ] I have added in line documentation to the code I modified

Short description of what this PR does:

• Adds alt texts for placeholder images

[SendGridDX]

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[SendGridDX]

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