INSTALL: Minor formatting correction in 'Legacy Windows and SSL' section

...as well as some rewording.

docs/INSTALL

@@ -473,12 +473,12 @@ Win32
 
    Legacy Windows and SSL
    ----------------------
-   WinSSL (Windows SSPI, more specifically Schannel), is the native SSL library
-   that comes with the Windows OS. WinSSL in Windows <= XP is not able to
-   connect to servers that no longer support the legacy handshakes and
-   algorithms used by those versions. If you will be using curl in one of those
-   earlier versions of Windows you should choose another SSL backend like
-   OpenSSL.
+
+   WinSSL (specifically SChannel from Windows SSPI), is the native SSL library
+   in Windows. However, WinSSL in Windows <= XP is unable to connect to servers
+   that no longer support the legacy handshakes and algorithms used by those
+   versions. If you will be using curl in one of those earlier versions of
+   Windows you should choose another SSL backend such as OpenSSL.
 
 Apple iOS and Mac OS X
 ======================