add timeline

scripts/phase2/README.md

-# Calculate `Actual` to `Expected` Claims.
+# Calculate `Actual` to `Expected` Claims for Short Term Disability (STD).
 
 ![actual to expected](https://git.unl.edu/carl.corder/acts-875/raw/master/img/actual-to-expected-claims.png)
 
-![std timeline](https://git.unl.edu/carl.corder/acts-875/raw/master/img/std-timeline.png)
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+![std timeline](https://git.unl.edu/carl.corder/acts-875/raw/master/img/std-timeline2.png)
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