Update version number and release notes

Author: peetw

NHibernate.Spatial.props

@@ -5,7 +5,7 @@
     <VersionMinor Condition="'$(VersionMinor)' == ''">1</VersionMinor>
     <VersionPatch Condition="'$(VersionPatch)' == ''">0</VersionPatch>
     <!-- NOTE: Set to "preXYZ" for pre-releases and leave blank for full releases -->
-    <VersionSuffix Condition="'$(VersionSuffix)' == ''">pre001</VersionSuffix>
+    <VersionSuffix Condition="'$(VersionSuffix)' == ''"></VersionSuffix>
 
     <!-- NOTE: Generally shouldn't need to edit anything below this line -->
     <VersionPrefix>$(VersionMajor).$(VersionMinor).$(VersionPatch)</VersionPrefix>

releasenotes.txt

@@ -13,6 +13,10 @@ https://nhibernate.jira.com/projects/NHSP
 ...and support questions to NH Users mailing list:
 http://groups.google.com/group/nhusers
 
+Build 5.1.0
+========================
+Targets NHibernate 5.1 and .NET Standard 2.0
+
 Build 5.0.0
 ========================
 Targets NHibernate 5.0.0 and .Net Framework 4.6.1