add a readme and neaten tt_tool

README.md

@@ -1,3 +1,20 @@
 # Tiny Tapeout tools
 
 Tools used mostly by the Tiny Tapeout github actions
+
+## Documentation
+
+* checks that basic fields are present in the info.yaml
+* create a PDF data sheet for this one design
+* create SVG and PNG renders of the project's GDS
+
+## Reports
+
+* routing & utilisation
+* yosys warnings
+* standard cell usage and summary
+
+## Configuration
+
+* creates a little TCL shim that tells OpenLane where the source is and the name of the top module
+* makes sure the top module is not called 'top'