Fix [CAUTION] usage format and warning during build

Author: Morganov

book/09-git-and-other-scms/sections/client-tfs.asc

@@ -21,10 +21,10 @@ Its support of TFVC features is very mature, since it uses the Visual Studio ass
 This does mean you'll need access to those assemblies, which means you need to install a recent version of Visual Studio (any edition since version 2010, including Express since version 2012), or the Visual Studio SDK.
 
 [CAUTION]
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+====
 Git-tf is End-of-Life (EOL), it will not get any updates.
 It is also no longer supported by Microsoft.
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+====
 
 Git-tf (whose home is at https://archive.codeplex.com/?p=gittf[]) is a Java project, and as such runs on any computer with a Java runtime environment.
 It interfaces with Git repositories through JGit (a JVM implementation of Git), which means it has virtually no limitations in terms of Git functions.