back4app outdated links on the parse server readme

[alyssoncm]

New Issue Checklist

• [x] I am not disclosing a vulnerability.
• [x] I am not just asking a question.
• [x] I have searched through existing issues.
• [x] I can reproduce the issue with the latest version of Parse Server.

Issue Description

back4app outdated links on the parse server readme

Steps to reproduce

Actual Outcome

Expected Outcome

Environment

Server

• Parse Server version: N/A
• Operating system: N/A
• Local or remote host (AWS, Azure, Google Cloud, Heroku, Digital Ocean, etc): N/A

Database

• System (MongoDB or Postgres): N/A
• Database version: N/A
• Local or remote host (MongoDB Atlas, mLab, AWS, Azure, Google Cloud, etc): N/A

Client

• SDK (iOS, Android, JavaScript, PHP, Unity, etc): N/A
• SDK version: N/A

Logs

[parse-github-assistant[bot]]

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[alyssoncm]

Update links of Back4App on Parse Server readme

[mtrezza]

Thanks Alysson! Closing via #7618