time: Add README to explain the purpose of the time extension library.

python-stdlib/time/README.md

@@ -0,0 +1,45 @@
+# time
+
+This library _extends_ the built-in [MicroPython `time`
+module](https://docs.micropython.org/en/latest/library/time.html#module-time) to
+include
+[`time.strftime()`](https://docs.python.org/3/library/datetime.html#strftime-and-strptime-behavior).
+
+`strftime()` is omitted from the built-in `time` module to conserve space.
+
+## Installation
+
+Use `mip` via `mpremote`:
+
+```bash
+> mpremote mip install time
+```
+
+See [Package management](https://docs.micropython.org/en/latest/reference/packages.html) for more details on using `mip` and `mpremote`.
+
+## Common uses
+
+`strftime()` is used when using a loggging [Formatter
+Object](https://docs.python.org/3/library/logging.html#formatter-objects) that
+employs
+[`asctime`](https://docs.python.org/3/library/logging.html#formatter-objects).
+
+For example:
+
+```python
+logging.Formatter('%(asctime)s | %(name)s | %(levelname)s - %(message)s')
+```
+
+The expected output might look like:
+
+```text
+Tue Feb 17 09:42:58 2009 | MAIN | INFO - test
+```
+
+But if this `time` extension library isn't installed, `asctime` will always be
+`None`:
+
+
+```text
+None | MAIN | INFO - test
+```