Creates a userspace for keymaps (#1559)

* create a user space

* adds example

* document, add readme.md

* jackhumbert userspace, ergodox keymap

users/_example/_example.c

@@ -0,0 +1,5 @@
+#include "_example.h"
+
+void my_custom_function(void) {
+    
+}

users/_example/_example.h

@@ -0,0 +1,8 @@
+#ifndef USERSPACE
+#define USERSPACE
+
+#include "quantum.h"
+
+void my_custom_function(void);
+
+#endif

users/_example/readme.md

@@ -0,0 +1,14 @@
+Copyright <year> <name> <email> @<github_username>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.

users/_example/rules.mk

@@ -0,0 +1 @@
+SRC += _example.c