Re #10819 Take format specification history back to version 1.8

Also corrects when `default-extensions`, `other-extensions`, `default-language` and `other-languages` were, in fact, first introduced.

Also supplies missing ('TBW') documentation for `other-languages`.

The introduction of the `exitcode-stdio-1.0` value is documented because this is needed to make sense of the changes that occurred in `cabal-version: 1.14` (see #10822).

Sources for changes:
* Change logs;
* Other documentation provided with released Cabal versions; and
* source code for published Cabal versions, including Haddock documentation and other code documentation.

Author: mpilgrem

doc/cabal-package-description-file.rst

@@ -1549,7 +1549,7 @@ system-dependent values for these fields.
       compiled twice, once as part of the library and again for the executable.
 
 .. pkg-field:: default-extensions: identifier list
-   :since: 1.12
+   :since: 1.10
 
     A list of Haskell extensions used by every module. These determine
     corresponding compiler options enabled for all files. Extension
@@ -1559,7 +1559,7 @@ system-dependent values for these fields.
     to be preprocessed with a C preprocessor.
 
 .. pkg-field:: other-extensions: identifier list
-   :since: 1.12
+   :since: 1.10
 
     A list of Haskell extensions used by some (but not necessarily all)
     modules. From GHC version 6.6 onward, these may be specified by
@@ -1588,7 +1588,7 @@ system-dependent values for these fields.
     :pkg-field:`other-extensions` declarations.
 
 .. pkg-field:: default-language: identifier
-   :since: 1.12
+   :since: 1.10
 
     Specifies a language standard or a group of language extensions to be activated for the project. In the case of GHC, `see here for details <https://downloads.haskell.org/ghc/latest/docs/users_guide/exts/control.html#controlling-extensions>`__.
 
@@ -1600,9 +1600,9 @@ system-dependent values for these fields.
     -  ``Haskell98``
 
 .. pkg-field:: other-languages: identifier
-   :since: 1.12
+   :since: 1.10
 
-   TBW
+    Specifies a language standard used by some (but not necessarily all) modules.
 
 .. pkg-field:: extensions: identifier list
    :deprecated: 1.12

doc/file-format-changelog.rst

@@ -298,9 +298,41 @@ relative to the respective preceding *published* version.
 ``cabal-version: 1.12``
 -----------------------
 
-* Change syntax of :pkg-field:`cabal-version` to support the new recommended
+* Change the syntax of :pkg-field:`cabal-version` to support the new recommended
   ``cabal-version: x.y`` style
 
+``cabal-version: ==1.10``
+-------------------------
 
+* Change the syntax of :pkg-field:`cabal-version` to require a version range of
+  the form ``cabal-version: >= x.y``. (Consequently, ``cabal-version: ==1.10``
+  is, itself, not valid syntax.)
+
+* New :pkg-field:`default-language` (to specify a default language standard when
+  one is not explicitly specified) and :pkg-field:`other-languages`
+  (for language standards used by some modules) added.
+
+* New :pkg-field:`default-extensions` (for Haskell language extensions used by
+  every module) and :pkg-field:`other-extensions` (for extensions used by some
+  modules) added. :pkg-field:`extensions` deprecated.
+
+* New :pkg-section:`test-suite` stanza for describing a package test suite
+  added.
+
+* ``exitcode-stdio-1.0`` is a valid value of the `type` field in a
+  :pkg-section:`test-suite` stanza.
+
+``cabal-version: ==1.8``
+------------------------
+
+* Added support for specifying the name of the package itself in the the
+  :pkg-field:`build-depends` of a :pkg-section:`executable` stanza. Cabal then
+  treats the executable as if it were in another package that depended on the
+  package.
+
+* The syntax for specifying package version ranges is expanded.
+
+* New :pkg-field:`license` types ``MIT`` and versioned ``GPL`` and ``LGPL``
+  added.
 
 .. include:: references.inc