typos: SOONG_DELVE and SOONG_UI_DELVE in README.md

leading colons raise "too many colons in address" error

Test: SOONG_DELVE=:5006 m
Bug: N/A
Change-Id: I311a9b807d97f3fc33411d44e5ec8dfe02376f55
diff --git a/README.md b/README.md
index caffd3d..1ab58af 100644
--- a/README.md
+++ b/README.md
@@ -596,14 +596,14 @@
 start the build with `SOONG_DELVE=<listen addr>` in the environment.
 For example:
 ```bash
-SOONG_DELVE=:5006 m nothing
+SOONG_DELVE=5006 m nothing
 ```
 
 To make `soong_ui` wait for a debugger connection, use the `SOONG_UI_DELVE`
 variable:
 
 ```
-SOONG_UI_DELVE=:5006 m nothing
+SOONG_UI_DELVE=5006 m nothing
 ```