s/master/main/

Test: treehugger
Change-Id: I2c975b2f5f92f23c7357b6f7e785578504298cc6
diff --git a/libc/malloc_debug/Config.cpp b/libc/malloc_debug/Config.cpp
index be577bc..77d2f02 100644
--- a/libc/malloc_debug/Config.cpp
+++ b/libc/malloc_debug/Config.cpp
@@ -409,7 +409,8 @@
 
 void Config::LogUsage() const {
   error_log("For malloc debug option descriptions go to:");
-  error_log("  https://android.googlesource.com/platform/bionic/+/master/libc/malloc_debug/README.md");
+  error_log(
+      "  https://android.googlesource.com/platform/bionic/+/main/libc/malloc_debug/README.md");
 }
 
 bool Config::GetOption(const char** options_str, std::string* option, std::string* value) {