Fix method UserAgentClientMinorVersion

Fix UserAgentClientMinorVersion. UserAgent may not always have the patchversion. So, need to parse for minor version slightly differently.
Only added comments to function 'UserAgentClientMajorVersion'

Ran the following tests

DECLARE		@UserAgent1 nvarchar(4000) = 'NuGet Command Line/2.8.4 (Microsoft Windows NT 6.3.9600.0)'
DECLARE		@UserAgent2 nvarchar(4000) = 'NuGet Command Line/2.8 '
DECLARE		@UserAgent3 nvarchar(4000) = 'NuGet Command Line/2.8 (Microsoft Windows NT 6.3.9600.0)'
DECLARE		@UserAgent4 nvarchar(4000) = 'NuGet Command Line/2.8'

SELECT		[dbo].[UserAgentClientMinorVersion-Test](@UserAgent1)
SELECT		[dbo].[UserAgentClientMinorVersion-Test](@UserAgent2)
SELECT		[dbo].[UserAgentClientMinorVersion-Test](@UserAgent3)
SELECT		[dbo].[UserAgentClientMinorVersion-Test](@UserAgent4)

SELECT		[dbo].[UserAgentClientMajorVersion-Test](@UserAgent1)
SELECT		[dbo].[UserAgentClientMajorVersion-Test](@UserAgent2)
SELECT		[dbo].[UserAgentClientMajorVersion-Test](@UserAgent3)
SELECT		[dbo].[UserAgentClientMajorVersion-Test](@UserAgent4)
Or even just commenting the chunks like this might help:

``` sql
        RETURN CAST(
			SUBSTRING(@value, 
				-- Start 1 character after the first dot after the /
                CHARINDEX('.', @value, CHARINDEX('/', @value) + 1) + 1,
				-- And determine our string length
                (
					-- CONCAT: Add a dot to the end to make sure we can find a dot
					-- Find the position of the next dot, starting 1 character after the first dot after the / (like we did above)
					CHARINDEX('.', CONCAT(@value, '.'), CHARINDEX('.', @value, CHARINDEX('/', @value) + 1) + 1))
					-- And now subtract the starting point we used to get the length of the string
					- ((CHARINDEX('.', @value, CHARINDEX('/', @value) + 1)) + 1
				)
            ) AS INT)
```