git-instaweb: add page (#4017)

pages/common/git-instaweb.md

@@ -0,0 +1,32 @@
+# git instaweb
+
+> Helper to launch a gitweb server.
+> More information: <https://git-scm.com/docs/git-instaweb>.
+
+- Launch a gitweb server for the current git repository:
+
+`git instaweb --start`
+
+- Listen only on localhost:
+
+`git instaweb --start --local`
+
+- Listen on a specific port:
+
+`git instaweb --start --port {{1234}}`
+
+- Use a specified http daemon:
+
+`git instaweb --start --httpd {{lighttpd|apache2|mongoose|plackup|webrick}}`
+
+- Also auto-launch a web browser:
+
+`git instaweb --start --browser`
+
+- Stop the currently running gitweb server:
+
+`git instaweb --stop`
+
+- Restart the currently running gitweb server:
+
+`git instaweb --restart`