Alternative tutorial on implementing samplers (#468)

* replaced the external sampler docs with a more straight-forward
tutorial on implementing samplers

* fixed reference to the impl samplers tutorial

* moved docs on implementing samplers

* revert changes to docs-16-using-turing-external-samplers

* make the `getparams` overload explicit

* renmaed NormalLogDensity to IsotropicNormalModel as per @mhauru suggestion

* replace underline with emph

* Apply suggestions from code review

Co-authored-by: Markus Hauru <[email protected]>

* fix formatting of summary

* removed type-piracy and added note on why we're using this example of MALA

---------

Co-authored-by: Markus Hauru <[email protected]>

Author: torfjelde

_quarto.yml

@@ -106,6 +106,8 @@ website:
             contents:
               - tutorials/docs-04-for-developers-abstractmcmc-turing/index.qmd
               - tutorials/docs-07-for-developers-variational-inference/index.qmd
+              - text: "Implementing Samplers"
+                href: tutorials/docs-17-implementing-samplers/index.qmd
 
 
   page-footer: