Help: Fix command-line synopsis markup syntax

Use `{}` to surround required parts instead of `()`.

Fixes: #17917

Help/manual/ccmake.1.rst

@@ -8,7 +8,7 @@ Synopsis
 
 .. parsed-literal::
 
- ccmake [<options>] (<path-to-source> | <path-to-existing-build>)
+ ccmake [<options>] {<path-to-source> | <path-to-existing-build>}
 
 Description
 ===========

Help/manual/cmake-gui.1.rst

@@ -9,7 +9,7 @@ Synopsis
 .. parsed-literal::
 
  cmake-gui [<options>]
- cmake-gui [<options>] (<path-to-source> | <path-to-existing-build>)
+ cmake-gui [<options>] {<path-to-source> | <path-to-existing-build>}
 
 Description
 ===========

Help/manual/cmake.1.rst

@@ -8,8 +8,8 @@ Synopsis
 
 .. parsed-literal::
 
- cmake [<options>] (<path-to-source> | <path-to-existing-build>)
- cmake [(-D <var>=<value>)...] -P <cmake-script-file>
+ cmake [<options>] {<path-to-source> | <path-to-existing-build>}
+ cmake [{-D <var>=<value>}...] -P <cmake-script-file>
  cmake --build <dir> [<options>...] [-- <build-tool-options>...]
  cmake --open <dir>
  cmake -E <command> [<options>...]

Help/manual/ctest.1.rst

@@ -13,7 +13,7 @@ Synopsis
  ctest [<options>]
  ctest <path-to-source> <path-to-build> --build-generator <generator>
        [<options>...] [-- <build-options>...] [--test-command <test>]
- ctest (-D <dashboard> | -M <model> -T <action> | -S <script> | -SP <script>)
+ ctest {-D <dashboard> | -M <model> -T <action> | -S <script> | -SP <script>}
        [-- <dashboard-options>...]
 
 Description