With the introduction of Gradle we lost the list of version properties
that were previously in the spring-boot-dependencies POM and were also
linked inside the documentation. This commit introduces an appendix
section in the docs and links the appropriate places to the new section
to restore discoverability.
See gh-19898
Update all dependencies declarations to use the form `scope(reference)`
rather than `scope reference`.
Prior to this commit we declared dependencies without parentheses unless
we were forced to add them due to an `exclude`.
Replace Gradle single quote strings with the double quote form
whenever possible. The change helps to being consistency to the
dependencies section where mostly single quotes were used, but
occasionally double quotes were required due to `${}` references.
