scm folders

reference/tools/scm/git.rst

@@ -3,6 +3,36 @@
 Git
 ===
 
+The ``Git`` helper is a thin wrapper over the ``git`` command. It can be used for different purposes:
+- Obtaining the current tag in the ``set_version()`` method to assign it to ``self.version``
+- Clone sources in third-party or open source package recipes in the ``source()`` method (in general, doing a ``download()`` or ``get()`` to fetch release tarballs will be preferred)
+- Capturing the "scm" coordinates (url, commit) of your own package sources in the ``export()`` method, to be able to reproduce a build from source later, retrieving the code in the ``source()`` method. See the :ref:`example of git-scm capture<examples_tools_scm_git_capture>`.
+
+The ``Git()`` constructor receives the current folder as argument, but that can be changed if necessary, for example, to clone the sources of some repo in ``source()``:
+
+
+.. code-block:: python
+
+     def source(self):
+        git = Git(self)  # by default, the current folder "."
+        git.clone(url="<repourl>", target="target") # git clone url target
+        # we need to cd directory for next command "checkout" to work
+        git.folder = "target"                       # cd target
+        git.checkout(commit="<commit>")             # git checkout commit
+
+
+An alternative, equivalent approach would be:
+
+.. code-block:: python
+
+     def source(self):
+        git = Git(self, "target")
+        # Cloning in current dir, not a children folder
+        git.clone(url="<repourl>", target=".")
+        git.checkout(commit="<commit>")
+
+
+
 .. currentmodule:: conan.tools.scm.git
 
 .. autoclass:: Git