[PATCH] submodule documentation: Reorder introductory paragraphs

[Stefan Beller <sbeller@google.com>]

It's better to start the man page with a description of what submodules
actually are instead of saying what they are not.

Reorder the paragraphs such that
the first short paragraph introduces the submodule concept,
the second paragraph highlights the usage of the submodule command,
the third paragraph giving background information,
and finally the fourth paragraph discusing alternatives such
as subtrees and remotes, which we don't want to be confused with.

This ordering deepens the knowledge on submodules with each paragraph.
First the basic questions like "How/what" will be answered, while the
underlying concepts will be taught at a later time.

Making sure it is not confused with subtrees and remotes is not really
enhancing knowledge of submodules itself, but rather painting the big
picture of git concepts, so you could also argue to have it as the second
paragraph. Personally I think this may confuse readers, specially
newcomers though.

Additionally to reordering the paragraphs, they have been slightly
reworded.

Signed-off-by: Stefan Beller <sbeller@google.com>
---

For now I used a part of Junios suggestion
    Submodules are not to be confused with remotes, which are other
    repositories of the same project;
    
I like the "are not to be confused" part, as they warn the reader
that there will be a paragraph not as concise but touching other
commands and topics.

 Documentation/git-submodule.txt | 50 ++++++++++++++++++-----------------------
 1 file changed, 22 insertions(+), 28 deletions(-)

diff --git a/Documentation/git-submodule.txt b/Documentation/git-submodule.txt
index 2c25916..d126c86 100644
--- a/Documentation/git-submodule.txt
+++ b/Documentation/git-submodule.txt
@@ -25,22 +25,17 @@ SYNOPSIS
 
 DESCRIPTION
 -----------
-Submodules allow foreign repositories to be embedded within
-a dedicated subdirectory of the source tree, always pointed
-at a particular commit.
+This command will inspect, update and manage submodules.
 
-They are not to be confused with remotes, which are meant mainly
-for branches of the same project; submodules are meant for
-different projects you would like to make part of your source tree,
-while the history of the two projects still stays completely
-independent and you cannot modify the contents of the submodule
-from within the main project.
-If you want to merge the project histories and want to treat the
-aggregated whole as a single project from then on, you may want to
-add a remote for the other project and use the 'subtree' merge strategy,
-instead of treating the other project as a submodule. Directories
-that come from both projects can be cloned and checked out as a whole
-if you choose to go that route.
+Submodules allow you to keep another Git repository in a subdirectory
+of your repository. The other repository has its own history, which does not
+interfere with the history of the current repository. This can be used to
+have external dependencies such as libraries for example.
+
+When cloning or pulling a repository containing submodules however,
+these will not be checked out by default; the 'init' and 'update'
+subcommands will maintain submodules checked out and at
+appropriate revision in your working tree.
 
 Submodules are composed from a so-called `gitlink` tree entry
 in the main repository that refers to a particular commit object
@@ -51,19 +46,18 @@ describes the default URL the submodule shall be cloned from.
 The logical name can be used for overriding this URL within your
 local repository configuration (see 'submodule init').
 
-This command will manage the tree entries and contents of the
-gitmodules file for you, as well as inspect the status of your
-submodules and update them.
-When adding a new submodule to the tree, the 'add' subcommand
-is to be used.  However, when pulling a tree containing submodules,
-these will not be checked out by default;
-the 'init' and 'update' subcommands will maintain submodules
-checked out and at appropriate revision in your working tree.
-You can briefly inspect the up-to-date status of your submodules
-using the 'status' subcommand and get a detailed overview of the
-difference between the index and checkouts using the 'summary'
-subcommand.
-
+Submodules are not to be confused with remotes, which are other
+repositories of the same project; submodules are meant for
+different projects you would like to make part of your source tree,
+while the history of the two projects still stays completely
+independent and you cannot modify the contents of the submodule
+from within the main project.
+If you want to merge the project histories and want to treat the
+aggregated whole as a single project from then on, you may want to
+add a remote for the other project and use the 'subtree' merge strategy,
+instead of treating the other project as a submodule. Directories
+that come from both projects can be cloned and checked out as a whole
+if you choose to go that route.
 
 COMMANDS
 --------
-- 
2.4.1.233.g3f9b614.dirty