framebuffer-spy: Update README

Author: asivery

framebuffer-spy/README.MD

@@ -1,4 +1,11 @@
 # framebuffer-spy
 
-Framebuffer-spy is a simple module which provides a single function: `void *getFramebufferAddress()` which returns the address of the framebuffer created by xochitl.
-**As of right now, only compatible with rMPP**
+Framebuffer-spy is a simple module which provides info on the rM tablet's framebuffer.
+
+Functions:
+
+- FramebufferConfig getFramebufferConfig() - returns a config object, as defined in `framebuffer-spy.h`
+- char *getConfigString() - returns a heap-allocated string-serialized FramebufferConfig object (`"0xAddress,width,height,type,bpl,requiresReload"`)
+- void refreshFramebuffer() - this function needs to be called before accessing the framebuffer data, if the `config.requiresReload` value is set
+
+Additionally, getConfigString is a xovi-message-broker export (`framebuffer-spy$getConfigString`), which makes it simple to access this data from software outside of xochitl.