[PATCH docs] user/bsp-build: Fix broken cross references.

[G S Niteesh Babu]

The QuickStartBSPBuild_Manual and QuickStartBSPBuild_RSB are
missing the underscore in front. This breaks any reference to
them from other sections.
---
 user/start/bsp-build.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/user/start/bsp-build.rst b/user/start/bsp-build.rst
index 33ecb29..59da2fd 100644
--- a/user/start/bsp-build.rst
+++ b/user/start/bsp-build.rst
@@ -29,7 +29,7 @@ use one of the listed methods to build the BSP.
 In the output in this section the base directory :file:`$HOME/quick-start` was
 replaced by ``$BASE``.
 
-.. QuickStartBSPBuild_RSB:
+.. _QuickStartBSPBuild_RSB:
 
 RSB BSP Build
 -------------
@@ -92,7 +92,7 @@ The RSB BSP build can be customised with following RSB command line options:
 If you have built a BSP with the RSB, you can move on to
 :ref:`QuickStartBSPTest`.
 
-.. QuickStartBSPBuild_Manual:
+.. _QuickStartBSPBuild_Manual:
 
 Manual BSP Build
 ----------------
-- 
2.17.1