Remove the runtime guide.

Now that libgreen is gone, this is all wrong.

Fixes #17923

Author: steveklabnik

Diff for: mk/docs.mk

@@ -27,7 +27,7 @@
 ######################################################################
 DOCS := index intro tutorial guide guide-ffi guide-macros guide-lifetimes \
 	guide-tasks guide-container guide-pointers guide-testing \
-	guide-runtime guide-plugin complement-bugreport \
+	guide-plugin complement-bugreport \
 	complement-lang-faq complement-design-faq complement-project-faq rust \
     rustdoc guide-unsafe guide-strings reference
 

Diff for: src/doc/guide-runtime.md

@@ -62,7 +62,6 @@ a guide that can help you out:
 * [Writing Unsafe and Low-Level Code](guide-unsafe.html)
 * [Macros](guide-macros.html)
 * [Testing](guide-testing.html)
-* [Rust's Runtime](guide-runtime.html)
 * [Compiler Plugins](guide-plugin.html)
 
 # Tools

Diff for: src/doc/index.md

@@ -15,7 +15,6 @@
 [type: text] src/doc/guide-macros.md $lang:doc/l10n/$lang/guide-macros.md
 [type: text] src/doc/guide-plugin.md $lang:doc/l10n/$lang/guide-plugin.md
 [type: text] src/doc/guide-pointers.md $lang:doc/l10n/$lang/guide-pointers.md
-[type: text] src/doc/guide-runtime.md $lang:doc/l10n/$lang/guide-runtime.md
 [type: text] src/doc/guide-strings.md $lang:doc/l10n/$lang/guide-strings.md
 [type: text] src/doc/guide-tasks.md $lang:doc/l10n/$lang/guide-tasks.md
 [type: text] src/doc/guide-testing.md $lang:doc/l10n/$lang/guide-testing.md