tools/autobuild,esp32: Template the generation of esp32 port deploy.md.

Allows two source files (ports/esp32/boards/deploy.md and
deploy_nativeusb.md for boards with only native USB) for all esp32
installation steps, with templated chip name and flash offset inserted via
string formatting.

The new files add more text to explain the esptool.py port auto-detection,
remove the unnecessary -z feature (already enabled by default), and add
a bit of troubleshooting and port detection info.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

tools/autobuild/build-downloads.py

@@ -91,7 +91,18 @@ def main(repo_path, output_path):
                 f.write("\n\n## Installation instructions\n")
             for deploy in blob["deploy"]:
                 with open(os.path.join(board_dir, deploy), "r") as fin:
-                    f.write(fin.read())
+                    body = fin.read()
+                    # any key in the board.json file can be substituted via Python str.format()
+                    try:
+                        body = body.format(**blob)
+                    except Exception as e:
+                        raise RuntimeError(
+                            "Failed to format deploy file {} according to {}: {}".format(
+                                fin.name, board_json, e
+                            )
+                        )
+                    f.write(body)
+                    f.write("\n")
 
     # Write the full index for the website to load.
     with open(os.path.join(output_path, "index.json"), "w") as f: