Recover docs for git vendoring

Cherry-picked from 5b08b8fe1019147fe489db17a9a8ae7ebe97f9e9 which failed
to update the book and was replaced in
1271bb4de0c0e0a085be239c2418af9c673ffc87.

diff --git a/src/doc/src/reference/source-replacement.md b/src/doc/src/reference/source-replacement.md
index 343a7296af46d941bcfe0b9a24f3d341a6c77e82..20099b29c910309255c3f904a9a6f25b71d1c82b 100644 (file)
--- a/src/doc/src/reference/source-replacement.md
+++ b/src/doc/src/reference/source-replacement.md
@@ -20,6 +20,12 @@ like so:
 [source.my-awesome-source]
 directory = "vendor"
 
+# Git sources can optionally specify a branch/tag/rev as well
+git = "https://example.com/path/to/repo"
+# branch = "master"
+# tag = "v1.0.1"
+# rev = "313f44e8"
+
 # The crates.io default source for crates is available under the name
 # "crates-io", and here we use the `replace-with` key to indicate that it's
 # replaced with our source above.