update docs, remove corealize (#4264)

* update docs, remove corealize

* handle 0 line count

* tensor schedule

docs/developer.md

@@ -5,3 +5,23 @@ Everything in [Tensor](tensor.md) is syntactic sugar around [function.py](functi
 ::: tinygrad.lazy.LazyBuffer
     options:
         show_source: false
+
+## Lowering
+
+The [scheduler](/tinygrad/engine/schedule.py) converts the graph of LazyBuffers into a list of `ScheduleItem`. `ast` specifies what compute to run, and `bufs` specifies what buffers to run it on.
+
+::: tinygrad.ops.ScheduleItem
+
+The code in [realize](/tinygrad/engine/realize.py) lowers `ScheduleItem` to `ExecItem` with
+
+::: tinygrad.engine.realize.lower_schedule
+
+## Execution
+
+Creating `ExecItem`, which has a run method
+
+::: tinygrad.engine.realize.ExecItem
+    options:
+        members: true
+
+Lists of `ExecItem` can be condensed into a single ExecItem with the Graph API (rename to Queue?)

docs/tensor.md

@@ -12,7 +12,8 @@
 
 ## tinygrad ops
 
-::: tinygrad.Tensor.corealize
+::: tinygrad.Tensor.schedule_with_vars
+::: tinygrad.Tensor.schedule
 ::: tinygrad.Tensor.realize
 ::: tinygrad.Tensor.replace
 ::: tinygrad.Tensor.assign