Java/Kotlin: Add a changenote for the lines-of-code changes

Author: igfoo

java/ql/src/change-notes/2023-10-20-lines-of-code.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* java/summary/lines-of-code now gives the total number of lines of Java and Kotlin code, and is the only query tagged `lines-of-code`. java/summary/lines-of-code-java and java/summary/lines-of-code-kotlin give the per-language counts.