Fixed commit link not autolinking

Author: agg23

README.md

@@ -18,7 +18,7 @@ This is a gate-level implementation of Pong, derived from the original schematic
 
 As Pong was implemented using 74-series TTL logic chips, driven in an asynchronous manner (outputs from one chip may clock another), certain steps had to be taken to ensure accurate synthesis.
 
-1. In addition to the 7.159 MHz primary clock used by Pong, a 28.636 MHz clock (4x the primary clock) is used to synchronize the various async parts of the ciruit. We take advantage of the time it takes logic gates to stablize in the original ciruit to gate updating values until an edge (typically rising) of the 28 MHz clock. This makes the logic formally synchronous, and avoids a series of problems that may arise during synthesis (see dc5953be54613d9eeb33aa888bffc915d3f99dce for an example of how changing synthesis can make or break the operation of async logic).
+1. In addition to the 7.159 MHz primary clock used by Pong, a 28.636 MHz clock (4x the primary clock) is used to synchronize the various async parts of the ciruit. We take advantage of the time it takes logic gates to stablize in the original ciruit to gate updating values until an edge (typically rising) of the 28 MHz clock. This makes the logic formally synchronous, and avoids a series of problems that may arise during synthesis (see [dc5953b](https://github.com/agg23/analogue-pong/commit/dc5953be54613d9eeb33aa888bffc915d3f99dce) for an example of how changing synthesis can make or break the operation of async logic).
 2. Several instances of combinational logic are converted to be synchronous to prevent the creation of combinational loops. These are denoted with a comment. In `paddle.vhd` in particular, leaving the output of the NAND `a7b` as a combinational expression resulted in the undefined clocking of the paddle height counter, resulting in flickering graphics and strange functionality.
 3. 555 timers are simulated as counters based off of the primary clock, with timing approximating those found in testing. Implementation based off of https://github.com/MiSTer-devel/Arcade-Pong_MiSTer/blob/master/rtl/paddle.v
 4. Horizontal sync timing in the original ciruit relies on a long ripple counter, which has the odd effect of ending `h_blank` _after_ the next rising edge of the clock (count is incremented on falling edge, and `h_blank` doesn't fall until after the rising edge). This is solved for by using the inverted primary clock as the synchronization clock for `h_blank`.