Add page about common errors (#1396)

* Update index.rst

Common errors page

* Create common-errors.rst

* Update common-errors.rst

* Use GHC 9.2 in CI runner (#1378)

* [haddock-api] remove .hspec-failures

Co-authored-by: Hécate Moonlight <Kleidukos@users.noreply.github.com>

doc/common-errors.rst

+Common Errors
+=============
+
+``parse error on input ‘-- | xxx’``
+-----------------------------------
+
+This is probably caused by the ``-- | xxx`` comment not following a declaration. I.e. use ``-- xxx`` instead. See :ref:`top-level-declaration`.
+
+``parse error on input ‘-- $ xxx’``
+----------------------------------
+
+You've probably commented out code like::
+
+  f x
+    $ xxx
+    
+``-- $`` is a special syntax for named chunks, see :ref:`named-chunks`. You can fix this by escaping the ``$``::
+
+  -- \$ xxx

doc/index.rst

@@ -12,6 +12,7 @@ Contents:
    intro
    invoking
    markup
+   common-errors
 
 
 Indices and tables

haddock-api/.hspec-failures

-FailureReport {failureReportSeed = 630888988, failureReportMaxSuccess = 100, failureReportMaxSize = 100, failureReportMaxDiscardRatio = 10, failureReportPaths = []}
\ No newline at end of file