False positive validating "Missing wiki links"

[ignasi35]

See lagom/lagom#615

• File was named: IntellijMaven.md.
• Link to file was intellijMaven (lowercase i)

Expected

Running markdownValidateDocs fails

[error] Could not find link intellijMaven at /Users/ignasi/git/projects/lightbend/lagom/docs/manual/java/gettingstarted/WhatsNext.md:13
[error] * [[Import an existing Maven project into Intellij|intellijMaven]]
[error]                                                    ^
[info] [fail] Missing wiki links test (1 errors)

Actual

Running markdownValidateDocs passes

[info] [pass] Missing wiki links test

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Bug seems to be in https://github.com/playframework/play-doc/blob/master/src/main/scala/play/doc/FileRepository.scala#L93 (uses equalsIgnoreCase instead of equals) but changing that could have side effects in other validations such as Duplicate markdown file name test