README: Document how to update java_tools to a custom version

README.md

diff --git a/README.md b/README.md
index e9b8156..f07c491 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,39 @@
 repository](https://github.com/bazelbuild/bazel). The source code will be moved 
 incrementally to this repository.
 
+# Upgrade Bazel project to use new java_tools version
+
+To upgrade Bazel project to use new java_tools releasem before new releases
+was pinned in new Bazel version and this version was released, add these lines
+to `WORKSPACE` file:
+
+```
+http_archive(
+    name = "remote_java_tools_linux",
+    sha256 = "37acb8380b1dd6c31fd27a19bf3da821c9b02ee93c6163fce36f070a806516b5",
+    urls = [
+        "https://mirror.bazel.build/bazel_java_tools/releases/javac11/v6.0/java_tools_javac11_linux-v6.0.zip",
+        "https://github.com/bazelbuild/java_tools/releases/download/javac11-v6.0/java_tools_javac11_linux-v6.0.zip",
+    ],
+)
+http_archive(
+    name = "remote_java_tools_windows",
+    sha256 = "384e138ca58842ea563fb7efbe0cb9c5c381bd4de1f6a31f0256823325f81ccc",
+    urls = [
+        "https://mirror.bazel.build/bazel_java_tools/releases/javac11/v6.0/java_tools_javac11_windows-v6.0.zip",
+        "https://github.com/bazelbuild/java_tools/releases/download/javac11-v6.0/java_tools_javac11_windows-v6.0.zip",
+    ],
+)
+http_archive(
+    name = "remote_java_tools_darwin",
+    sha256 = "5a9f320c33424262e505151dd5c6903e36678a0f0bbdaae67bcf07f41d8c7cf3",
+    urls = [
+        "https://mirror.bazel.build/bazel_java_tools/releases/javac11/v6.0/java_tools_javac11_darwin-v6.0.zip",
+        "https://github.com/bazelbuild/java_tools/releases/download/javac11-v6.0/java_tools_javac11_darwin-v6.0.zip",
+    ],
+)
+```
+
 # Releases
 
 The releases can be found under [java_tools/releases](https://github.com/bazelbuild/java_tools/releases)