chore(travis): use lean-build@googlegroups

.travis.osx.yml

@@ -119,6 +119,6 @@ install:
 notifications:
   email:
     recipients:
-    - leansmt-dev@googlegroups.com
+    - lean-build@googlegroups.com
     on_success: always
     on_failure: always

.travis.windows.yml

@@ -80,6 +80,6 @@ after_script:
 notifications:
   email:
     recipients:
-    - leansmt-dev@googlegroups.com
+    - lean-build@googlegroups.com
     on_success: always
     on_failure: always

.travis.yml

@@ -312,6 +312,6 @@ after_script:
 notifications:
   email:
     recipients:
-     - leansmt-dev@googlegroups.com
+     - lean-build@googlegroups.com
     on_success: always
     on_failure: always

doc/make/travis.md

@@ -14,6 +14,6 @@ We just have to go to our fork page at github; select `settings` (it is an icon
 select `Service Hooks`; select `Travis`; and provide the required information.
 We must have an account at Travis.
 
-By default, build reports are sent to the [leansmt-dev](https://groups.google.com/forum/#!forum/leansmt-dev) Google group.
+By default, build reports are sent to the [lean-build](https://groups.google.com/forum/#!forum/lean-build) Google group.
 You can change that by modifying the file [.travis.yml](../../.travis.yml) in the Lean root directory. The file contains a
 `recipients:` entry.