Update some docstrings and comments

* contrib/lisp/org-e-ascii.el (org-e-ascii-table,
  org-e-ascii--table-cell-width): Update docsring.
* contrib/lisp/org-e-html.el (org-e-html-table): Update docstring.
* contrib/lisp/org-e-latex.el (org-e-latex-table): Update docstring.
* contrib/lisp/org-e-odt.el (org-e-odt-table): Update docstring.

contrib/lisp/org-e-ascii.el

@@ -1668,7 +1668,8 @@ holding contextual information."
 
 (defun org-e-ascii-table (table contents info)
   "Transcode a TABLE element from Org to ASCII.
-CONTENTS is nil.  INFO is a plist holding contextual information."
+CONTENTS is the contents of the table.  INFO is a plist holding
+contextual information."
   (let ((caption (org-e-ascii--build-caption table info)))
     (concat
      ;; Possibly add a caption string above.
@@ -1686,11 +1687,14 @@ CONTENTS is nil.  INFO is a plist holding contextual information."
 (defun org-e-ascii--table-cell-width (table-cell info)
   "Return width of TABLE-CELL.
 
+INFO is a plist used as a communication channel.
+
 Width of a cell is determined either by a width cookie in the
-same column as the cell, or by the length of its contents.
+same column as the cell, or by the maximum cell's length in that
+column.
 
 When `org-e-ascii-table-widen-columns' is non-nil, width cookies
-are ignored. "
+are ignored."
   (or (and (not org-e-ascii-table-widen-columns)
 	   (org-export-table-cell-width table-cell info))
       (let* ((max-width 0)

contrib/lisp/org-e-html.el

@@ -2937,7 +2937,8 @@ communication channel."
 
 (defun org-e-html-table (table contents info)
   "Transcode a TABLE element from Org to HTML.
-CONTENTS is nil.  INFO is a plist holding contextual information."
+CONTENTS is the contents of the table.  INFO is a plist holding
+contextual information."
   (case (org-element-property :type table)
     ;; Case 1: table.el table.  Convert it using appropriate tools.
     (table.el (org-e-html-table--table.el-table table info))

contrib/lisp/org-e-latex.el

@@ -1998,7 +1998,8 @@ contextual information."
 
 (defun org-e-latex-table (table contents info)
   "Transcode a TABLE element from Org to LaTeX.
-CONTENTS is nil.  INFO is a plist holding contextual information."
+CONTENTS is the contents of the table.  INFO is a plist holding
+contextual information."
   (cond
    ;; Case 1: verbatim table.
    ((or org-e-latex-tables-verbatim

contrib/lisp/org-e-odt.el

@@ -4113,7 +4113,8 @@ communication channel."
 
 (defun org-e-odt-table (table contents info)
   "Transcode a TABLE element from Org to HTML.
-CONTENTS is nil.  INFO is a plist holding contextual information."
+CONTENTS is the contents of the table.  INFO is a plist holding
+contextual information."
   (case (org-element-property :type table)
     (table.el nil)
     (t

contrib/lisp/org-export.el

@@ -3300,10 +3300,13 @@ code."
 
 ;;;; For Tables
 ;;
-;; `org-export-table-has-special-column-p' and
+;; `org-export-table-has-special-column-p' and and
 ;; `org-export-table-row-is-special-p' are predicates used to look for
 ;; meta-information about the table structure.
 ;;
+;; `org-table-has-header-p' tells when the rows before the first rule
+;;  should be considered as table's header.
+;;
 ;; `org-export-table-cell-width', `org-export-table-cell-alignment'
 ;; and `org-export-table-cell-borders' extract information from
 ;; a table-cell element.
@@ -3313,6 +3316,14 @@ code."
 ;; `org-export-table-cell-address', given a table-cell object, returns
 ;; the absolute address of a cell. On the other hand,
 ;; `org-export-get-table-cell-at' does the contrary.
+;;
+;; `org-export-table-cell-starts-colgroup-p',
+;; `org-export-table-cell-ends-colgroup-p',
+;; `org-export-table-row-starts-rowgroup-p',
+;; `org-export-table-row-ends-rowgroup-p',
+;; `org-export-table-row-starts-header-p' and
+;; `org-export-table-row-ends-header-p' indicate position of current
+;; row or cell within the table.
 
 (defun org-export-table-has-special-column-p (table)
   "Non-nil when TABLE has a special column.