Fix docgen to print True/False for boolean attributes, not 1/0

Fixes #3240

RELNOTES: none
PiperOrigin-RevId: 225379721

src/main/java/com/google/devtools/build/docgen/RuleDocumentationAttribute.java

diff --git a/src/main/java/com/google/devtools/build/docgen/RuleDocumentationAttribute.java b/src/main/java/com/google/devtools/build/docgen/RuleDocumentationAttribute.java
index 2fde0f1..922c331 100644
--- a/src/main/java/com/google/devtools/build/docgen/RuleDocumentationAttribute.java
+++ b/src/main/java/com/google/devtools/build/docgen/RuleDocumentationAttribute.java
@@ -175,7 +175,7 @@
     String prefix = "; default is ";
     Object value = attribute.getDefaultValueForTesting();
     if (value instanceof Boolean) {
-      return prefix + ((Boolean) value ? "1" : "0");
+      return prefix + ((Boolean) value ? "True" : "False");
     } else if (value instanceof Integer) {
       return prefix + String.valueOf(value);
     } else if (value instanceof String && !(((String) value).isEmpty())) {