add info to reference

Author: igagis

wiki/Reference.adoc

@@ -628,7 +628,7 @@ $(eval $(prorab-build-lib))
 - `this_soname` - so name for dynamic library. **Mandatory**
 - `this_headers_dir` - root directory of the header files which are to be installed with the library. Relative to `$(d)`.
 - `this_headers_install_dir` - header files installation destination directory. Relative to `$(DESTDIR)$(PREFIX)/include`. Can be empty, then header files are installed straight to `$(DESTDIR)$(PREFIX)/include`.
-- `this_install_hdrs` - list of header files to install. Relative to `$(d)`. If `this_install_hdrs`, `this_install_c_hdrs` and `this_install_cxx_hdrs` are empty, then the `this_headers_dir` directory is searched recursively for C (`.h`) and {cpp} header files (`$(this_dot_hxx)`). The `install` target will install these header files to `$(DESTDIR)$(PREFIX)/include/$(this_headers_install_dir)` preserving directory structure under `this_headers_dir` directory. Also, the `test` target will test these header files for compilation, same as headers from `this_hdrs`, but with no compilation flags, except `-std=...` filtered from `$(this_cflags)`/`$(this_cxxflags)`.
+- `this_install_hdrs` - list of header files to install. Relative to `$(d)`. If `this_install_hdrs`, `this_install_c_hdrs` and `this_install_cxx_hdrs` are empty, then the `this_headers_dir` directory is searched recursively for C (`.h`) and {cpp} header files (`$(this_dot_hxx)`). The `install` target will install these header files to `$(DESTDIR)$(PREFIX)/include/$(this_headers_install_dir)` preserving directory structure under `this_headers_dir` directory. Also, the `test` target will test these header files for compilation, same as headers from `this_hdrs`, but with no compilation flags, except `-std=...` filtered from `$(this_cflags)`/`$(this_cxxflags)`. To disable installing headers, assign `$(prorab_space)` to this variable.
 - `this_install_c_hdrs` - list of `c`-only header files to install. See `this_install_hdrs` for details. Relative to `$(d)`. The `test` target will test these header files for compilation.
 - `this_install_cxx_hdrs` - list of `c++`-only header files to install. See `this_install_hdrs` for details. Relative to `$(d)`. The `test` target will test these header files for compilation.
 - `this_static_lib_only` - disables building of shared library. If `true` only static library is built. Otherwise both, shared and static libraries are built. Defaults to empty.