update phoenix guide title to be generic (#3879)

check_urls=free-programming-books.md
Signed-off-by: Ntechgaun <coolsamar207@gmail.com>

free-programming-books.md

@@ -1226,7 +1226,7 @@ Kerridge (PDF) (email address *requested*, not required)
 
 #### Phoenix
 
-* [Phoenix v1.3.0 Guide](https://hexdocs.pm/phoenix/overview.html) (HTML)
+* [Phoenix Framework Guide](https://hexdocs.pm/phoenix/overview.html) (HTML)
 * [Versioned APIs with Phoenix](https://elviovicosa.com/freebies/versioned-apis-with-phoenix-by-elvio-vicosa.pdf) - Elvio Vicosa (PDF)