READMEのKnown bugsを修正した

Author: ytr-sakamoto

README.md

@@ -28,7 +28,7 @@ java [PROGRAM-ID]
 ## The progress of the development
 
 The functions in the following "implemented" list are tested using [NIST COBOL85 test suite](https://www.itl.nist.gov/div897/ctg/cobol_form.htm)
-gnd **95%** of the test cases are passed.
+and **95%** of the test cases are passed.
 
 Implemented.
 
@@ -48,5 +48,5 @@ Not Implemented.
 Known bugs
 
 * Cannot call inline programs.
-* Rewrite wrong data to indexed files with alternate keys.
-* Some sort statements produces wrong data.
+* Rewrite wrong data to indexed files with alternate keys in some cases.
+* Under some conditions, SORT statements produce wrong data.