Add hosted docs link to docs/README.md

Closes GH-13633

docs/README.md

@@ -1,8 +1,9 @@
 # php-src docs
 
-This is the home of the php-src internal documentation. It is in very early stages, but is intended
-to become the primary place where new information about php-src is documented. Over time, it is
-expected to replace various mediums like:
+This is the home of the php-src internal documentation, hosted at
+[php.github.io/php-src/](https://php.github.io/php-src/). It is in very early stages, but is
+intended to become the primary place where new information about php-src is documented. Over time,
+it is expected to replace various mediums like:
 
 * https://www.phpinternalsbook.com/
 * https://wiki.php.net/internals
@@ -21,7 +22,8 @@ That's it! You can view the documentation under `./build/html/index.html` in you
 
 ## Formatting
 
-The files in this documentation are formatted using the [``rstfmt``](https://github.com/dzhu/rstfmt) tool.
+The files in this documentation are formatted using the
+[``rstfmt``](https://github.com/dzhu/rstfmt) tool.
 
 ```bash
 rstfmt -w 100 source