[PATCH 3/7] api-parse-options.adoc: document hidden and OPT_*_F option macros

[Christian Couder <christian.couder@gmail.com>]

In "Documentation/technical/api-parse-options.adoc", the list of option
macros does not mention the `OPT_*_F()` macro variants that take a
trailing `flags` argument, nor the `OPT_HIDDEN_GROUP()` and
`OPT_HIDDEN_BOOL()` convenience macros.

Now that a previous commit documents the per-option flags, let's
document these macros too:

  - Add a paragraph explaining the `OPT_*_F` convention and how it
    relates to the per-option flags.

  - Document `OPT_HIDDEN_GROUP()`, introduced in a previous commit,
    right after `OPT_GROUP()`.

  - Document `OPT_HIDDEN_BOOL()` right after `OPT_BOOL()`.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 Documentation/technical/api-parse-options.adoc | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/technical/api-parse-options.adoc b/Documentation/technical/api-parse-options.adoc
index fb4580e755..0e10327d07 100644
--- a/Documentation/technical/api-parse-options.adoc
+++ b/Documentation/technical/api-parse-options.adoc
@@ -213,6 +213,13 @@ Macros
 
 There are some macros to easily define options:
 
+Many of the macros below have an `_F` variant (for example `OPT_BOOL_F`,
+`OPT_STRING_F`, `OPT_INTEGER_F`, `OPT_SET_INT_F`, `OPT_BIT_F` and
+`OPT_CALLBACK_F`) that takes an additional trailing `flags` argument.
+That argument is the bitwise-or of the per-option flags described in the
+"Option flags" section above; the non-`_F` macros are simply defined
+with `flags` set to `0`.
+
 `OPT__ABBREV(&int_var)`::
 	Add `--abbrev[=<n>]`.
 
@@ -236,10 +243,21 @@ There are some macros to easily define options:
 	describes the group or an empty string.
 	Start the description with an upper-case letter.
 
+`OPT_HIDDEN_GROUP(description)`::
+	Like `OPT_GROUP()`, but the group header carries
+	`PARSE_OPT_HIDDEN`, so it is only shown by `--help-all` and not
+	by `-h`. Use it to label a group that contains only hidden
+	options, which would otherwise show an empty header under `-h`.
+
 `OPT_BOOL(short, long, &int_var, description)`::
 	Introduce a boolean option. `int_var` is set to one with
 	`--option` and set to zero with `--no-option`.
 
+`OPT_HIDDEN_BOOL(short, long, &int_var, description)`::
+	Like `OPT_BOOL()`, but the option carries `PARSE_OPT_HIDDEN`,
+	so it is hidden from `-h` while still being shown by
+	`--help-all`.
+
 `OPT_COUNTUP(short, long, &int_var, description)`::
 	Introduce a count-up option.
 	Each use of `--option` increments `int_var`, starting from zero
-- 
2.55.0.185.g9120d2b5c0