manual.texi Tim's suggestion added

Docs/manual.texi

@@ -21530,8 +21530,8 @@ very little resources.
 
 @item @code{ft_min_word_len}
 The minimum length of the word to be included in a @code{FULLTEXT} index.
-@strong{Note: @code{FULLTEXT} index have to be rebuilt after changing
-this variable.}
+@strong{Note: @code{FULLTEXT} index have to be rebuilt (e.g. with
+@code{OPTIMIZE TABLE}) after changing this variable.}
 
 @item @code{ft_max_word_len}
 The maximum length of the word to be included in a @code{FULLTEXT} index.
@@ -21541,7 +21541,7 @@ this variable.}
 @item @code{ft_max_word_len_sort}
 The maximum length of the word in a @code{FULLTEXT} index
 to be used in fast index recreation method in
-@code{REPAIR}, @code{CREATE INDEX},  or
+@code{REPAIR}, @code{CREATE INDEX}, @code{OPTIMIZE TABLE}, or
 @code{ALTER TABLE}.  Longer words are inserted the slow way.
 The rule of the thumb is as follows: with @code{ft_max_word_len_sort}
 increasing, @strong{MySQL} will create bigger temporary files
@@ -21550,8 +21550,8 @@ fewer keys in one sort block (againg, decreasing the efficiency).
 When @code{ft_max_word_len_sort} is too small, instead,
 @strong{MySQL} will insert a lot of words into index the slow way -
 but short words will be inserted very fast. It applies only to
-Index recreation during @code{REPAIR}, @code{CREATE INDEX}, or
-@code{ALTER TABLE}.
+index recreation during @code{REPAIR}, @code{CREATE INDEX},
+@code{OPTIMIZE TABLE}, or @code{ALTER TABLE}.
 
 @item @code{have_bdb}
 @code{YES} if @code{mysqld} supports Berkeley DB tables. @code{DISABLED}
@@ -28310,7 +28310,7 @@ unless you know what you are doing!
 Minimal length of word to be indexed is defined by @strong{MySQL}
 variable @code{ft_min_word_length}. @xref{SHOW VARIABLES}.
 Change it to the value you prefer, and rebuild
-your @code{FULLTEXT} indexes.
+your @code{FULLTEXT} indexes (e.g. with @code{OPTIMIZE TABLE}).
 
 @item
 The stopword list is defined in @code{myisam/ft_static.c}