Clean up TBDs in changelog

libraries/base/changelog.md

 # Changelog for [`base` package](http://hackage.haskell.org/package/base)
 
-## 4.15.0.0 *TBA*
-  * TODO
-
-## 4.14.0.0 *TBA*
+## 4.14.0.0 *Jan 2020
   * Bundled with GHC 8.10.1
 
   * Add a `TestEquality` instance for the `Compose` newtype.

libraries/template-haskell/changelog.md

 # Changelog for [`template-haskell` package](http://hackage.haskell.org/package/template-haskell)
 
-## 2.16.0.0 *TBA*
+## 2.16.0.0 *Jan 2020*
+
+  * Bundled with GHC 8.10.1
 
   * Add support for tuple sections. (#15843) The type signatures of `TupE` and
     `UnboxedTupE` have changed from `[Exp] -> Exp` to `[Maybe Exp] -> Exp`.
@@ -24,6 +26,8 @@
 
 ## 2.15.0.0 *May 2019*
 
+  * Bundled with GHC 8.8.1
+
   * In `Language.Haskell.TH.Syntax`, `DataInstD`, `NewTypeInstD`, `TySynEqn`,
     and `RuleP` now all have a `Maybe [TyVarBndr]` argument, which contains a
     list of quantified type variables if an explicit `forall` is present, and
@@ -46,6 +50,8 @@
 
 ## 2.14.0.0 *September 2018*
 
+  * Bundled with GHC 8.6.1
+
   * Introduce an `addForeignFilePath` function, as well as a corresponding
     `qAddForeignFile` class method to `Quasi`. Unlike `addForeignFile`, which
     takes the contents of the file as an argument, `addForeignFilePath` takes