Format fix 2005/persano/README.md

Also update .gitignore.

2005/persano/.gitignore

@@ -1 +1,2 @@
 persano
+foo.gif

2005/persano/README.md

@@ -1,9 +1,8 @@
 # Best of show
 
 Mauro Persano  
-    São Paulo
 Brazil  
-    mauro_persano@yahoo.com
+<mauro_persano@yahoo.com>  
 
 ## To build:
 
@@ -23,10 +22,11 @@ make
 ./persano 3 16 > knot3-16.gif
 ```
 
-Open the GIF file with a viewer capable of displaying animated GIFs and
+Open the [GIF](https://en.wikipedia.org/wiki/GIF) file with a viewer capable of
-watch closely at the bottom of the picture (you may need to use
+displaying animated GIFs and watch closely at the bottom of the picture (you may
-"gifsicle" - a great tool to manipulate animated GIFs - to slow down the
+need to use [gifsicle](https://www.lcdf.org/gifsicle/) - a great tool to
-animation and to compress the GIFs generated by the entry).
+manipulate animated GIFs - to slow down the animation and to compress the GIFs
+generated by the entry).
 
 ## Judges' remarks:
 
@@ -39,31 +39,32 @@ What needs to be done to fix the problem?
 
 Solving the author's exercises below may or may not help.
 
-At the time of judging, the approximation of π used in the program could
+At the time of judging, the approximation of
-not be found on mathworld.com.
+[π](https://en.wikipedia.org/wiki/Pi) used in the program could not be found on
+<https://mathworld.wolfram.com>.
 
 ## Author's remarks:
 
-### NAME
 
-**knot**
+**knot** writes animated GIF images of rendered [torus
-> writes animated GIF images of rendered torus knots to standard output.
+knots](https://en.wikipedia.org/wiki/Torus_knot) to standard output.
 
 ### SYNOPSIS
 
 ```sh
-knot p q [num frames]
+./persano p q [num frames]
 ```
 
 ### DESCRIPTION
 
-A (p,q)-torus knot is a closed, non-intersecting curve on the surface of
+A (p,q)-[torus knot](https://en.wikipedia.org/wiki/Torus_knot) is a closed,
-a torus in R3 that winds p times around one cycle of the torus and q
+non-intersecting curve on the surface of a
-times around the other. p and q should be coprime; otherwise, the
+[torus](https://en.wikipedia.org/wiki/Torus) in R3 that winds `p` times around
-resulting curve will _not_ be a knot (that is, imagining the resulting
+one cycle of the torus and `q` times around the other. `p` and `q` should be
-curve as a loop of rubber, there will be a way to bend, twist and
+[coprime](https://en.wikipedia.org/wiki/Coprime_integers); otherwise, the
-stretch it, without cutting it [1], until it ends up looking just like a
+resulting curve will _not_ be a knot (that is, imagining the resulting curve as
-circle embedded in R3 [2]).
+a loop of rubber, there will be a way to bend, twist and stretch it, without
+cutting it [1], until it ends up looking just like a circle embedded in R3 [2]).
 
 Sample usage:
 
@@ -72,13 +73,14 @@ Sample usage:
 ```
 
 writes a non-animated GIF (a single frame) stream of a rendered trefoil
-knot to the file foo.gif.
+knot to the file `foo.gif`.
 
 ```sh
 ./persano 5 2
 ```
 
-writes a GIF stream with a rendering of Solomon's Seal knot to standard
+writes a GIF stream with a rendering of [Solomon's Seal
+knot](https://en.wikipedia.org/wiki/Solomon%27s_knot) to standard
 output; since the number of frames is not specified, an animation with
 40 frames will be written.
 
@@ -91,9 +93,10 @@ The program writes fully valid GIF 89 streams.
 It is suggested that the output be viewed with a program capable of
 displaying animated GIFs, such as almost any graphical HTTP browser.
 
-Due to code size constraints, full LZW compression was not implemented
+Due to code size constraints, full [LZW
-[3]. In fact, the output images are even somewhat expanded, thanks to
+compression](https://en.wikipedia.org/wiki/LZ77_and_LZ78#LZW) was not
-GIF overhead.
+implemented [3]. In fact, the output images are even somewhat expanded, thanks
+to GIF overhead.
 
 The GIF format supports only a limited number of bits per pixel, so the
 program uses ordered dithering to emulate full RGB output.
@@ -101,7 +104,7 @@ program uses ordered dithering to emulate full RGB output.
 ### PORTABILITY
 
 The program was tested on Linux, with gcc 3.1; Cygwin, with gcc 3.3; and
-Solaris/Sparc, with Sun's C compiler.
+Solaris/SPARC, with Sun's C compiler.
 
 The only major portability issue should be reliance on ASCII.
 
@@ -116,7 +119,8 @@ smoother by increasing the number of polygons.
 
 2. (2 points) Figure out how to change the radius of the tube cross section.
 
-  3. (5 points) Locate the famous transcendental constant π in the code.
+3. (5 points) Locate the famous transcendental constant
+[π](https://en.wikipedia.org/wiki/Pi) in the code.
 
 ### FOOTNOTES