Finish table documentation.

MODULES.md

@@ -621,6 +621,7 @@ substituted.
                    [#:border-style (*table-border-style*)]
                    [#:ansi #f])
 
+* ```tbl``` - list of lists with cell data
 * ```#:table-border``` - if ```#t```, the table has outer border
 * ```#:row-border``` - if ```#t```, the rows are separated by borders
 * ```#:col-border``` - if ```#t```, the columns are separated by borders
@@ -629,3 +630,26 @@ substituted.
 * ```#:ansi``` - if ```#t```, all cell line strings are terminated
   with ```a:default```
 
+The table ```tbl``` is represented as a list of rows where each row is
+a list of cells that hold arbitrary values that are converted to
+string when rendering the table.
+
+Before rendering the table, the following steps are performed:
+
+* The table is made rectangular - that is all rows are extended by
+  empty strings to have the same length.
+* All non-string cells are converted to string using ```sprintf```
+* All cells are split into list of strings representing the lines of
+  text inside them.
+* For each row, all cells are extended by empty strings to have
+  matching number of lines of text inside them.
+* For each column, all lines of text inside all of the cells are
+  padded with spaces to have uniform width.
+
+Then each table row is converted to list of strings adding column
+separators and table borders as required. These lists are then joined
+with row separators and possibly prefixed and suffixed by top and
+bottom table border.
+
+The resulting list of strings is joined with newline character as the
+separator.