Clean out some TODOs

More can be written, but this will do for now.

doc/manual/source/store/building.md

@@ -1,13 +1,10 @@
 # Building
 
-TODO
-
 ## Normalizing derivation inputs
 
-TODO
+- Each input must be [realised] prior to building the derivation in question.
 
-Each input must be [realised] prior to building the derivation in question.
-At that point, the derivation can be *normalized*, by replacing each input deriving path with its store path --- which we now know since we've realised it.
+- Once this is done, the derivation is *normalized*, replacing each input deriving path with its store path, which we now know from realising the input.
 
 ## Builder Execution
 
@@ -68,10 +65,7 @@ The [`builder`](./drv.md#builder) is executed as follows:
 - The temporary directory is removed (unless the `-K` option was
   specified).
 
-- If the build was successful, Nix scans each output path for
-  references to input paths by looking for the hash parts of the input
-  paths. Since these are potential runtime dependencies, Nix registers
-  them as dependencies of the output paths.
+## Processing outputs and Reference scanning
 
 - After the build, Nix sets the last-modified timestamp on all files
   in the build result to 1 (00:00:01 1/1/1970 UTC), sets the group to
@@ -83,6 +77,10 @@ The [`builder`](./drv.md#builder) is executed as follows:
   deployment have no concept of ownership information, and because it
   makes the build result dependent on the user performing the build.
 
-## Processing outputs and Reference scanning
+- If the build was successful, Nix scans each output path for
+  references to input paths by looking for the hash parts of the input
+  paths. Since these are potential runtime dependencies, Nix registers
+  them as dependencies of the output paths.
 
-TODO
+  Nix also scans for references to other outputs' paths in the same way, because outputs are allowed to refer to each other.
+  If the outputs' references to each other form a cycle, this is an error, because the references of store objects much be acyclic.

doc/manual/source/store/drv.md

@@ -295,7 +295,8 @@ Under this extended model, `DerivingPath`s are thus inductively built up from an
 
 ### Encoding {#deriving-path-encoding}
 
-The encoding is adjusted in a very simplest way, merely displaying the same
+The encoding is adjusted in the natural way, encoding the `drv` field recursively using the same deriving path encoding.
+The result of this is that it is possible to have a chain of `^<output-name>` at the end of the final string, as opposed to just a single one.
 
 > **Example**
 >