doc: Adjusting tags in release notes to eliminate global conflict for…

… singlehtml builds

Change tags shared-slot-rn and capi2-rn tags to reduce conflict tags in
skiboot-5.7.rst

For the singlehtml builds to work correctly, the same tags cannot be used
globally in any files.  These two tags, shared-slot-rn and capi2-rn, also
appear in skiboot-5.7.rst. To eliminate, the
tags had a suffix "-rc1" for both the definition and use of each tag.

Signed-off-by: Jeff Scheel <scheel@us.ibm.com>
[stewart: use 5.7 in tag just to be complete]
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

doc/release-notes/skiboot-5.7-rc1.rst

@@ -31,8 +31,8 @@ New Features
 New features in this release for POWER9 systems:
 
 - In Memory Counters (IMC) (See :ref:`imc` for details)
-- phb4: Activate shared PCI slot on witherspoon (see :ref:`Shared Slot <shared-slot-rn>`)
-- phb4 capi (i.e. CAPI2): Enable capi mode for PHB4 (see :ref:`CAPI on PHB4 <capi2-rn>`)
+- phb4: Activate shared PCI slot on witherspoon (see :ref:`Shared Slot <shared-slot-5.7-rc1-rn>`)
+- phb4 capi (i.e. CAPI2): Enable capi mode for PHB4 (see :ref:`CAPI on PHB4 <capi2-5.7-rc1-rn>`)
 
 New feature for IBM FSP based systems:
 
@@ -258,7 +258,7 @@ PCI/PHB4
   operations) is only available with P9 DD2. A new patch will be provided
   to support this feature.
 
-.. _capi2-rn:
+.. _capi2-5.7-rc1-rn:
 
 - phb4 capi (i.e. CAPI2): Enable capi mode for PHB4
 
@@ -304,7 +304,7 @@ PCI/PHB4
 
   Only partially tested and contends with some DD1 errata, but it's a start.
 
-.. _shared-slot-rn:
+.. _shared-slot-5.7-rc1-rn:
 
 - phb4: Activate shared PCI slot on witherspoon