docs: move local plugins file to the correct directory

docs/contributing/gatsby-style-guide.md

@@ -205,7 +205,7 @@ Here are some folder name examples:
 - querying-data-with-graphql
 
 Note: Just to clarify, you can include special characters in the article title
-but _not_ in the `.md` file name or folder name (e.g. Title: What is GraphQL? and Folder Name:
+but _not_ in the `.md` file name or folder name (e.g. title: What is GraphQL? and Folder Name:
 what-is-graphql).
 
 ## Grammar and formatting

docs/docs/creating-a-local-plugin.md

@@ -1,5 +1,5 @@
 ---
-Title: Creating a Local Plugin
+title: Creating a Local Plugin
 ---
 
 If a plugin is only relevant to your specific use-case, or if you’re developing a plugin and want a simpler workflow, a locally defined plugin is a convenient way to create and manage your plugin code.

docs/loading-plugins-from-your-local-plugins-folder.md → docs/docs/loading-plugins-from-your-local-plugins-folder.md

@@ -1,5 +1,5 @@
 ---
-Title: Loading Plugins from Your Local Plugins Folder
+title: Loading Plugins from Your Local Plugins Folder
 ---
 
 Gatsby can also load plugins from the your local website plugins folder which is a folder named `plugins` in the website's root directory.