Update Pre/PostAction Alias note [skip appveyor]

The initial version of PR #4872 proposed to document that pre- and
post-actions on an alias have no effect if the alias has no action
itself. Subsequently, PR #4874 was merged to change this behavior so
that statement is backed out, but the other proposed doc improvements
in this area are retained.

Signed-off-by: Mats Wichmann <mats@linux.com>

Author: mwichmann

CHANGES.txt

@@ -18,7 +18,7 @@ RELEASE  VERSION/DATE TO BE FILLED IN LATER
   From Mats Wichmann:
     - Fix typos in CCFLAGS test. Didn't affect the test itself, but
       didn't correctly apply the DefaultEnvironment speedup.
-    - Clarify that pre/post actions on an alias apply to the alias' action.
+    - Clarify how pre/post actions on an alias work.
 
 
 RELEASE 4.9.0 -  Sun, 02 Mar 2025 17:22:20 -0700

RELEASE.txt

@@ -53,7 +53,7 @@ DOCUMENTATION
   typo fixes, even if they're mentioned in src/CHANGES.txt to give
   the contributor credit)
 
-- Clarify that pre/post actions on an alias apply to the alias' action.
+- Clarify how pre/post actions on an alias work.
 
 DEVELOPMENT
 -----------

SCons/Environment.xml

@@ -380,10 +380,7 @@ AddPostAction(foo, Chmod('$TARGET', "a-x"))
 <para>
 If a <parameter>target</parameter> is an Alias target,
 <parameter>action</parameter> is associated with the
-action of the alias,
-not of any targets that alias may refer to.
-Thus, &AddPostAction; will have no effect
-if called on an alias which has no action.
+action of the alias, if specified.
 </para>
 
 </summary>
@@ -425,10 +422,13 @@ before the action step that specifically
 generates the specified target(s).
 It may not always be obvious
 if the process is multi-step - for example,
-when building an executable program from a specified source
-<filename>.c</filename>
-file, &scons; will build an intermediate object file first,
-and the pre-action will follow this.
+if you use the &Program; builder to
+construct an executable program from a
+<filename>.c</filename> source file,
+&scons; builds an intermediate object file first;
+the pre-action is invoked after this step
+and just before the link command to
+generate the executable program binary.
 Example:
 </para>
 
@@ -437,17 +437,6 @@ foo = Program('foo.c')
 AddPreAction(foo, 'echo "Running pre-action"')
 </example_commands>
 
-<para>
-The specified pre-action is executed before
-&scons;
-calls the link command that actually
-generates the executable program binary
-<filename>foo</filename>,
-but after compiling the
-<filename>foo.c</filename>
-file into an object file:
-</para>
-
 <screen>
 $ scons -Q
 gcc -o foo.o -c foo.c
@@ -459,10 +448,7 @@ gcc -o foo foo.o
 <para>
 If a <parameter>target</parameter> is an Alias target,
 <parameter>action</parameter> is associated with the
-action of the alias,
-not with any targets that alias may refer to.
-Thus, &AddPreAction; will have no effect
-if called on an alias which has no action.
+action of the alias, if specified.
 </para>
 
 </summary>