Document glob patterns

Bug: 71906438
Test: none
Change-Id: Ic18f2dc5d91b30ff2b5beb8047d98591ba70ee00

1 files changed, 8 insertions, 0 deletions

diff --git a/README.md b/README.md
index b3239e9aa..3549b0253 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,14 @@ all Android.bp files.
 For a list of valid module types and their properties see
 [$OUT_DIR/soong/.bootstrap/docs/soong_build.html](https://go/Android.bp).
 
+### Globs
+
+Properties that take a list of files can also take glob patterns.  Glob
+patterns can contain the normal Unix wildcard `*`, for example "*.java". Glob
+patterns can also contain a single `**` wildcard as a path element, which will
+match zero or more path elements.  For example, `java/**/*.java` will match
+`java/Main.java` and `java/com/android/Main.java`.
+
 ### Variables
 
 An Android.bp file may contain top-level variable assignments: