Move style guide to docs dir (#5174)

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,3 +1,4 @@
 <!--
-Before submitting a PR, please read https://deno.land/std/manual.md#contributing
+Before submitting a PR, please read
+https://github.com/denoland/deno/blob/master/docs/contributing.md
 -->

docs/contributing.md

@@ -1,6 +1,6 @@
 # Contributing
 
-- Read the [style guide](style_guide.md).
+- Read the [style guide](contributing/style_guide.md).
 
 - Please don't make [the benchmarks](https://deno.land/benchmarks.html) worse.
 
@@ -16,7 +16,7 @@
 ## Development
 
 Instructions on how to build from source can be found
-[here](./building-from-source).
+[here](./contributing/building_from_source.md).
 
 ## Submitting a Pull Request
 

docs/toc.json

@@ -65,6 +65,7 @@
     "children": {
       "building_from_source": "Building from source",
       "development_tools": "Development tools",
+      "style_guide": "Style guide",
       "architecture": "Architecture"
     }
   },