Docs: fix markdown in various files, update the README mildly

sky/specs/README.md

Index: sky/specs/README.md
diff --git a/sky/specs/README.md b/sky/specs/README.md
index 2817894fee4c8f45901cf49940ce8b1c11d0b625..1cef0fdb358dd33e7e68eac33e50920bfa91a42f 100644
--- a/sky/specs/README.md
+++ b/sky/specs/README.md
@@ -7,20 +7,20 @@ they can refer to binary resources like images and fonts.
 Sky files
 ---------
 
-Conventional MIME type: ```text/sky```, though this type is neither
+Conventional MIME type: ``text/sky``, though this type is neither
 necessary nor sufficient to indicate that a file is a Sky file; only
 the signature matters for type dispatch of Sky files.
 
-Conventional extension: ```.sky```
+Conventional extension: ``.sky``
 
 Signatures:
 
 For application files, one of the following:
- ```23 21 6d 6f 6a 6f 20 6d 6f 6a 6f 3a 73 6b 79 0a``` ("```#!mojo mojo:sky\n```")
- ```23 21 6d 6f 6a 6f 20 6d 6f 6a 6f 3a 73 6b 79 0d``` ("```#!mojo mojo:sky\r```")
- ```23 21 6d 6f 6a 6f 20 6d 6f 6a 6f 3a 73 6b 79 20``` ("```#!mojo mojo:sky ```")
+ ``23 21 6d 6f 6a 6f 20 6d 6f 6a 6f 3a 73 6b 79 0a`` ("``#!mojo mojo:sky\n``")
+ ``23 21 6d 6f 6a 6f 20 6d 6f 6a 6f 3a 73 6b 79 0d`` ("``#!mojo mojo:sky\r``")
+ ``23 21 6d 6f 6a 6f 20 6d 6f 6a 6f 3a 73 6b 79 20`` ("``#!mojo mojo:sky ``")
 
 For module files, one of the following:
- ```53 4b 59 20 4d 4f 44 55 4c 45 0a``` ("```SKY MODULE\n```")
- ```53 4b 59 20 4d 4f 44 55 4c 45 0d``` ("```SKY MODULE\r```")
- ```53 4b 59 20 4d 4f 44 55 4c 45 20``` ("```SKY MODULE ```")
+ ``53 4b 59 20 4d 4f 44 55 4c 45 0a`` ("``SKY MODULE\n``")
+ ``53 4b 59 20 4d 4f 44 55 4c 45 0d`` ("``SKY MODULE\r``")
+ ``53 4b 59 20 4d 4f 44 55 4c 45 20`` ("``SKY MODULE ``")