Add NEP1 to documentation.

Changes:
  - Added NEP 1 to the documentation set.
  - Modified nimdoc's css to add additional spacing between list entries, as well as between code blocks.
  - Added a warning to nimdoc.css for future developers.

web/documentation.txt

@@ -14,6 +14,9 @@ Nim's Documentation
     - | `Language Manual <docs/manual.html>`_
       | The Nim manual is a draft that will evolve into a proper specification.
 
+    - | `Nim Style Guide <nep1.html>`_
+      | The stylistic conventions that Nim's official projects adhere to.
+
     - | `Compiler User Guide <docs/nimc.html>`_
       | The user guide lists command line arguments, special features of the
         compiler, etc.

web/website.ini

@@ -31,7 +31,7 @@ file: ticker.txt
 [Documentation]
 doc: "endb;intern;apis;lib;manual.txt;tut1;tut2;nimc;overview;filters"
 doc: "tools;niminst;nimgrep;gc;estp;idetools;docgen;koch;backends.txt"
-doc: "nimfix.txt;nimsuggest.txt"
+doc: "nimfix.txt;nimsuggest.txt;nep1.txt"
 pdf: "manual.txt;lib;tut1;tut2;nimc;niminst;gc"
 srcdoc2: "system.nim"
 srcdoc2: "core/macros;pure/marshal;core/typeinfo;core/unsigned"