Merge pull request #1763 from kariya-mitsuru/fix-signingkey

Fix user.signingkey example

Author: ben

book/07-git-tools/sections/signing.asc

@@ -29,7 +29,7 @@ Once you have a private key to sign with, you can configure Git to use it for si
 
 [source,console]
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-$ git config --global user.signingkey 0A46826A
+$ git config --global user.signingkey 0A46826A!
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 Now Git will use your key by default to sign tags and commits if you want.