Formatting changes to Alpha readme.md (#2781)

Formatting changes to Alpha readme.md (#2781)

* alpha with firmware added to list of keyboards, ready to push

* revised according to drashna's fixes

* keymap -> layout?

* fixed macro and improved layout issuesOC

* Update rules.mk

* Update alpha.h

* Update and rename keyboards/alpha/layouts/default/28_alpha/keymap.c to keyboards/alpha/keymaps/default/keymap.c

* alpha/readme.md added according to qmk templateOC

* resolved a careless merge conflict

* bugfix

* Fixed /keyboards/alpha/readme.md formatting issues