[PATCH] doc: explain why file: URLs and bundles don't mix

[Alyssa Ross <hi@alyssa.is>]

Signed-off-by: Alyssa Ross <hi@alyssa.is>
---
 Documentation/urls.txt | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/Documentation/urls.txt b/Documentation/urls.txt
index b05da95788..c83d9f859e 100644
--- a/Documentation/urls.txt
+++ b/Documentation/urls.txt
@@ -43,14 +43,24 @@ syntaxes may be used:
 - \file:///path/to/repo.git/
 
 ifndef::git-clone[]
-These two syntaxes are mostly equivalent, except when cloning, when
-the former implies --local option. See linkgit:git-clone[1] for
-details.
+These two syntaxes are mostly equivalent, with some exceptions:
+
+- When cloning, the former implies --local option. See
+  linkgit:git-clone[1] for details.
+
+- The latter is implemented using linkgit:git-upload-pack[1], which
+  expects its repository to be a directory, and therefore does not
+  work for bundles (see linkgit:git-bundle[1]).
 endif::git-clone[]
 
 ifdef::git-clone[]
-These two syntaxes are mostly equivalent, except the former implies
---local option.
+These two syntaxes are mostly equivalent, with some exceptions:
+
+- The former implies --local option.
+
+- The latter is implemented using linkgit:git-upload-pack[1], which
+  expects its repository to be a directory, and therefore does not
+  work for bundles (see linkgit:git-bundle[1]).
 endif::git-clone[]
 
 When Git doesn't know how to handle a certain transport protocol, it
-- 
2.21.0