Add suggested alias for bazelrc import location

See https://github.com/bazelbuild/bazel/issues/6319
diff --git a/.bazelrc b/.bazelrc
new file mode 100644
index 0000000..bc31c54
--- /dev/null
+++ b/.bazelrc
@@ -0,0 +1,3 @@
+# load bazelrc from the legacy location
+# as recommended in https://github.com/bazelbuild/bazel/issues/6319
+import %workspace%/tools/bazel.rc
diff --git a/tools/bazel.rc b/tools/bazel.rc
index 5b10721..bfdbc0c 100644
--- a/tools/bazel.rc
+++ b/tools/bazel.rc
@@ -1,3 +1,8 @@
+# bazelrc file
+# bazel >= 0.18 looks for %workspace%/.bazelrc (which redirects here)
+# Older bazel versions look for %workspace%/tools/bazel.rc (this file)
+# See https://github.com/bazelbuild/bazel/issues/6319
+
 build --client_env=CC=clang
 build --copt=-DGRPC_BAZEL_BUILD