Integrate version badge from spring.io [DATAMONGO-1462]

[spring-projects-issues]

Mark Paluch opened DATAMONGO-1462 and commented

Add version badge from spring.io and replace fixed version numbers in the repository readme file

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Issue Links:

• DATACASS-321 Integrate version badge from spring.io

• DATAJPA-932 Integrate version badge from spring.io

• DATAREDIS-536 Integrate version badge from spring.io

• DATAREST-856 Integrate version badge from spring.io

• DATASOLR-318 Integrate version badge from spring.io

Referenced from: commits 318ba53