Update README for Kong 1.0.x~ user

[wassan128]

Thank you for your offering this plugin.

I'm using Kong 1.2.x. At this version, /apis endpoint has replaced, so I couldn't add plugin.

I examined Kong Admin's API document and notice this change happened at vesion 1.0.x boundary.

[coveralls]

Pull Request Test Coverage Report for Build 137

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 96.296%

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Totals
Change from base Build 134:	0.0%
Covered Lines:	130
Relevant Lines:	135

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💛 - Coveralls