doc/manual.txt: added 32bit pkgs, system accounts and notes sections.

doc/manual.txt

@@ -596,6 +596,72 @@ libfoo.so.1 foo-1.0_1
 - The second field specified the package name and minimal version required.
 - A third optional field specifies the architecture (rarely used).
 
+Creating users/groups at runtime
+--------------------------------
+
+There's a trigger along with some variables that are specifically to create
+**system users and groups** when the binary package is being configured.
+The following variables can be used for this purpose:
+
+*system_groups*::
+ This specifies the names of the new *system groups* to be created, separated
+by blanks. Optionally the **gid** can be specified by delimiting it with a
+colon, i.e `system_groups="mygroup:78"` or `system_groups="foo blah:8000"`.
+
+*system_accounts*::
+ This specifies the names of the new **system users/groups** to be created,
+separated by blanks, i.e `system_accounts="foo blah"`. Additional variables
+for the **system accounts** can be specified to change its behavior:
+
+ - `<account>_homedir`: the home directory for the user. If unset defaults to
+   `/`.
+ - `<account>_shell`: the shell for the new user. If unset defaults to
+   `/sbin/nologin`.
+ - `<account>_descr`: the description for the new user. If unset defaults to
+   `<user> unprivileged user`.
+ - `<account>_groups`: additional groups to be added to for the new user.
+
+The **system user** is created by using a dynamically allocated **uid/gid** in your system
+and it's created as a `system account`. A new group will be created for the
+specified `system account` and used exclusived for this purpose.
+
+32bit packages
+--------------
+
+32bit packages are built automatically when the builder is x86 (32bit), but
+there are some variables that can change the behavior:
+
+*lib32depends*::
+ If this variable is set, dependencies listed here will be used rather than
+those detected automatically by xbps-src and **depends**. Please note that
+dependencies must be specified with version comparators, i.e
+`lib32depends="foo>=0 blah<2.0"`.
+
+*lib32disabled*::
+ If this variable is set, no 32bit package will be built. Please note that
+this variable if used in the global scope it will disable 32bit packages for
+the **main package and its subpackages**.
+
+*lib32files*::
+ Additional files to be added to the **32bit** package. This expect absolute
+ paths separated by blanks, i.e `lib32files="/usr/bin/blah
+/usr/include/blah."`.
+
+*lib32mode*::
+ If unset, only shared libraries and pkg-config files will be copied to the
+**32bit** package. If set to `full` all files will be copied as is.
+
+Notes
+-----
+
+- Make sure that all software is configured to use the `/usr` prefix.
+- Binaries should always be installed at `/usr/bin` and `/usr/sbin`.
+- Manual pages should always be installed at `/usr/share/man` and
+uncompressed.
+- If a software provides **shared libraries** and headers, probably you should
+create a `development package` that contains `headers`, `static libraries`
+and other files required for development (not required at runtime).
+
 Contributing via git
 --------------------
 You can fork the `xbps-packages` git repository on github and then set up