Update link to other installation options

Author: kraai

www/index.html

@@ -182,7 +182,7 @@
   <img src="https://www.rust-lang.org/logos/rust-logo-blk.svg" alt="" />
   rustup is an official Rust project.
   <br/>
-  <a href="https://github.com/rust-lang/rustup/#other-installation-methods">other installation options</a>
+  <a href="https://rust-lang.github.io/rustup/installation/other.html">other installation options</a>
   &nbsp;&middot;&nbsp;
   <a href="https://rust-lang.github.io/rustup-components-history/">component availability</a>
   &nbsp;&middot;&nbsp;