[amber-docs] RFR: adding links to Inside.java and Dev.java

[Chad Arimura]

Creating this PR because I wanted to point to Amber's wiki but realized it didn't point back to all the aggregated Amber content on Inside.java. I included Dev.java as well but can remove if it's not specific enough. It does have a lot of Amber coverage throughout.

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Commit messages:
 - adding links to Inside.java and Dev.java. The former is very specific to Amber. The latter is a general learning page for many of the Amber topics. Let me know if I should remove the Dev.java link.

Changes: https://git.openjdk.java.net/amber-docs/pull/12/files
 Webrev: https://webrevs.openjdk.java.net/?repo=amber-docs&pr=12&range=00
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/amber-docs/pull/12.diff
  Fetch: git fetch https://git.openjdk.java.net/amber-docs pull/12/head:pull/12

PR: https://git.openjdk.java.net/amber-docs/pull/12