UNDER_THE_HOOD.md: add links section.

Author: peterhinch

UNDER_THE_HOOD.md

@@ -351,14 +351,14 @@ def get_event_loop(args):
 
 # 8. Links
 
-[Initial discussion of priority I/O scheduling](https://github.com/micropython/micropython/issues/2664)  
+Initial discussion of priority I/O scheduling [here](https://github.com/micropython/micropython/issues/2664)  
 
 PR enabling stream device drivers to be written in Python 
 [PR #3836: io.IOBase](https://github.com/micropython/micropython/pull/3836).
 Includes discussion of the read/write bug.  
 
 My outstanding uasyncio PR's:
-[PR #287: fast I/O](https://github.com/micropython/micropython-lib/pull/287)
+[PR #287: fast I/O](https://github.com/micropython/micropython-lib/pull/287) and
 [PR #292: error reporting](https://github.com/micropython/micropython-lib/pull/292)
 
 This caught my attention as worthwhile: