Rework getting started guide to package description

Author: mpilgrem

doc/other_resources.md

@@ -17,3 +17,10 @@ There are lots of resources available for learning more about Stack:
 * The [haskell-stack tag on Stack Overflow](http://stackoverflow.com/questions/tagged/haskell-stack)
 * [Another getting started with Stack tutorial](http://seanhess.github.io/2015/08/04/practical-haskell-getting-started.html)
 * [Why is Stack not Cabal?](https://www.fpcomplete.com/blog/2015/06/why-is-stack-not-cabal)
+
+Package description format specifications supported by Stack:
+
+* Cabal's: a
+  [Cabal file](https://cabal.readthedocs.io/en/stable/cabal-package-description-file.html)
+* Hpack's: a
+  [`package.yaml` file](https://github.com/sol/hpack?tab=readme-ov-file#documentation)

doc/tutorial/building_existing_projects.md

@@ -1,6 +1,6 @@
   <div class="hidden-warning"><a href="https://docs.haskellstack.org/"><img src="https://cdn.jsdelivr.net/gh/commercialhaskell/stack/doc/img/hidden-warning.svg"></a></div>
 
-# 3. Building existing projects
+# 5. Building existing projects
 
 Alright, enough playing around with simple projects. Let's take an open source
 package and try to build it. We'll be ambitious and use

doc/tutorial/building_your_project.md

@@ -1,6 +1,6 @@
 <div class="hidden-warning"><a href="https://docs.haskellstack.org/"><img src="https://cdn.jsdelivr.net/gh/commercialhaskell/stack/doc/img/hidden-warning.svg"></a></div>
 
-# 2. Building your project
+# 4. Building your project
 
 The [`stack build`](../commands/build_command.md) command is the heart of Stack.
 It is the engine that powers building your code, testing it, getting

doc/tutorial/cabal_flags_and_ghc_options.md

@@ -1,6 +1,6 @@
   <div class="hidden-warning"><a href="https://docs.haskellstack.org/"><img src="https://cdn.jsdelivr.net/gh/commercialhaskell/stack/doc/img/hidden-warning.svg"></a></div>
 
-# 8. Cabal flags and GHC options
+# 10. Cabal flags and GHC options
 
 There are two common ways to alter how a package will install: with Cabal flags
 and with GHC options.

doc/tutorial/executing_commands.md

@@ -1,6 +1,6 @@
   <div class="hidden-warning"><a href="https://docs.haskellstack.org/"><img src="https://cdn.jsdelivr.net/gh/commercialhaskell/stack/doc/img/hidden-warning.svg"></a></div>
 
-# 10. Executing commands
+# 12. Executing commands
 
 We've already used `stack exec` multiple times in this guide. As you've likely
 already guessed, it allows you to run executables, but with a slightly modified