Document added/updated functions

Also renames `addHeaders` to `addHeadersDirectory` for clarity.

lib/std/Build.zig

@@ -1560,21 +1560,22 @@ pub fn addObjCopy(b: *Build, source: LazyPath, options: Step.ObjCopy.Options) *S
  return Step.ObjCopy.create(b, source, options);
 }
 
-///`dest_rel_path` is relative to install prefix path
+/// `dest_rel_path` is relative to install prefix path
 pub fn addInstallFile(b: *Build, source: LazyPath, dest_rel_path: []const u8) *Step.InstallFile {
  return b.addInstallFileWithDir(source, .prefix, dest_rel_path);
 }
 
-///`dest_rel_path` is relative to bin path
+/// `dest_rel_path` is relative to bin path
 pub fn addInstallBinFile(b: *Build, source: LazyPath, dest_rel_path: []const u8) *Step.InstallFile {
  return b.addInstallFileWithDir(source, .bin, dest_rel_path);
 }
 
-///`dest_rel_path` is relative to lib path
+/// `dest_rel_path` is relative to lib path
 pub fn addInstallLibFile(b: *Build, source: LazyPath, dest_rel_path: []const u8) *Step.InstallFile {
  return b.addInstallFileWithDir(source, .lib, dest_rel_path);
 }
 
+/// `dest_rel_path` is relative to header path
 pub fn addInstallHeaderFile(b: *Build, source: LazyPath, dest_rel_path: []const u8) *Step.InstallFile {
  return b.addInstallFileWithDir(source, .header, dest_rel_path);
 }

lib/std/Build/Step/Compile.zig

@@ -443,6 +443,9 @@ pub fn create(owner: *std.Build, options: Options) *Compile {
  return self;
 }
 
+/// Marks the specified header for installation alongside this artifact.
+/// When a module links with this artifact, all headers marked for installation are added to that
+/// module's include search path.
 pub fn installHeader(cs: *Compile, source: LazyPath, dest_rel_path: []const u8) void {
  const b = cs.step.owner;
  const installation: HeaderInstallation = .{ .file = .{
@@ -454,7 +457,10 @@ pub fn installHeader(cs: *Compile, source: LazyPath, dest_rel_path: []const u8)
  installation.getSource().addStepDependencies(&cs.step);
 }
 
-pub fn installHeaders(
+/// Marks headers from the specified directory for installation alongside this artifact.
+/// When a module links with this artifact, all headers marked for installation are added to that
+/// module's include search path.
+pub fn installHeadersDirectory(
  cs: *Compile,
  source: LazyPath,
  dest_rel_path: []const u8,
@@ -471,10 +477,16 @@ pub fn installHeaders(
  installation.getSource().addStepDependencies(&cs.step);
 }
 
+/// Marks the specified config header for installation alongside this artifact.
+/// When a module links with this artifact, all headers marked for installation are added to that
+/// module's include search path.
 pub fn installConfigHeader(cs: *Compile, config_header: *Step.ConfigHeader) void {
  cs.installHeader(config_header.getOutput(), config_header.include_path);
 }
 
+/// Forwards all headers marked for installation from `lib` to this artifact.
+/// When a module links with this artifact, all headers marked for installation are added to that
+/// module's include search path.
 pub fn installLibraryHeaders(cs: *Compile, lib: *Compile) void {
  assert(lib.kind == .lib);
  const b = cs.step.owner;

lib/std/Build/Step/WriteFile.zig

@@ -126,6 +126,9 @@ pub fn addCopyFile(wf: *WriteFile, source: std.Build.LazyPath, sub_path: []const
  return file.getPath();
 }
 
+/// Copy files matching the specified exclude/include patterns to the specified subdirectory
+/// relative to this step's generated directory.
+/// The returned value is a lazy path to the generated subdirectory.
 pub fn addCopyDirectory(
  wf: *WriteFile,
  source: std.Build.LazyPath,

test/standalone/install_headers/build.zig

@@ -32,7 +32,7 @@ pub fn build(b: *std.Build) void {
  \\}
  ) });
 
- libfoo.installHeaders(.{ .path = "include" }, "foo", .{ .exclude_extensions = &.{".ignore_me.h"} });
+ libfoo.installHeadersDirectory(.{ .path = "include" }, "foo", .{ .exclude_extensions = &.{".ignore_me.h"} });
  libfoo.installHeader(b.addWriteFiles().add("d.h",
  \\#define FOO_D "D"
  \\