Include a README with some sample error messages

kotlin-power-assert/src/main/kotlin/com/bnorm/power/PowerAssertCallTransformer.kt

@@ -190,7 +190,7 @@ class PowerAssertCallTransformer(
             val indentations = sorted.map { it.indentation }
 
             addArgument(irString(buildString {
-              append(":").newline()
+              newline()
               append(callSource).newline()
               var last = -1
               for (i in indentations) {

kotlin-power-assert/src/test/kotlin/com/bnorm/power/test.kt

@@ -34,7 +34,7 @@ fun main() {
   assert(hello.length == "World".substring(1, 4).length)
 }""",
       """
-Assertion failed:
+Assertion failed
 assert(hello.length == "World".substring(1, 4).length)
        |     |      |          |               |
        |     |      |          |               3
@@ -55,7 +55,7 @@ fun main() {
   assert(hello.reversed() == emptyList<String>())
 }""",
       """
-Assertion failed:
+Assertion failed
 assert(hello.reversed() == emptyList<String>())
        |     |          |  |
        |     |          |  []
@@ -74,7 +74,7 @@ fun main() {
   assert(1 == 2) { "Not equal" }
 }""",
       """
-Not equal:
+Not equal
 assert(1 == 2) { "Not equal" }
          |
          false