Add comments for make targets

Signed-off-by: Hasan Turken <turkenh@gmail.com>

Makefile

@@ -173,11 +173,21 @@ CROSSPLANE_NAMESPACE = upbound-system
 -include build/makelib/local.xpkg.mk
 -include build/makelib/controlplane.mk
 
+# This target requires the following environment variables to be set:
+# - UPTEST_EXAMPLE_LIST, a comma-separated list of examples to test
+# - UPTEST_DATASOURCE_PATH, see https://github.com/upbound/uptest#injecting-dynamic-values-and-datasource
 uptest: $(UPTEST) $(KUBECTL) $(KUTTL)
 	@$(INFO) running automated tests
 	@KUBECTL=$(KUBECTL) KUTTL=$(KUTTL) $(UPTEST) e2e "${UPTEST_EXAMPLE_LIST}" --setup-script=cluster/test/setup.sh || $(FAIL)
 	@$(OK) running automated tests
 
+uptest-local:
+	@$(WARN) "this target is deprecated, please use 'make uptest' instead"
+
+# This target requires the following environment variables to be set:
+# - UPTEST_CLOUD_CREDENTIALS, cloud credentials for the provider being tested, e.g. export UPTEST_CLOUD_CREDENTIALS=$(cat ~/.aws/credentials)
+# - UPTEST_EXAMPLE_LIST, a comma-separated list of examples to test
+# - UPTEST_DATASOURCE_PATH, see https://github.com/upbound/uptest#injecting-dynamic-values-and-datasource
 e2e: build controlplane.up local.xpkg.deploy.provider.$(PROJECT_NAME) uptest
 
 .PHONY: uptest e2e