Move pages under tldr, lint run.sh, update docs

tldr/git-submodule

@@ -0,0 +1,25 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# git submodule
+
+> Inspects, updates and manages submodules.
+> More information: <https://git-scm.com/docs/git-submodule>.
+
+- Install a repository's specified submodules:
+
+`git submodule update --init --recursive`
+
+- Add a Git repository as a submodule:
+
+`git submodule add {{repository_url}}`
+
+- Add a Git repository as a submodule at the specified directory:
+
+`git submodule add {{repository_url}} {{path/to/directory}}`
+
+- Update every submodule to its latest commit:
+
+`git submodule foreach git pull`