Merge pull request #183 from metabr/fix-typo

fix typo

Author: ben

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

@@ -112,7 +112,7 @@ The stdin/stdout protocol is the same as git-credential, but they use a slightly
 
 For the `store` and `erase` actions, no response is required (Git ignores it anyway).
 For the `get` action, however, Git is very interested in what the helper has to say.
-If the helper doesn't know anything useful, it can simply exit with no output, but it it does know, it should augment the provided information with the information it has stored.
+If the helper doesn't know anything useful, it can simply exit with no output, but if it does know, it should augment the provided information with the information it has stored.
 The output is treated like a series of assignment statements; anything provided will replace what Git already knows.
 
 Here's the same example from above, but skipping git-credential and going straight for git-credential-store: