DOC: configuration.txt: fix various typos

This was done using automatic spellcheck.

(cherry picked from commit 8525fd95b2467609a70a62375009374e58d22829)
[wt: removed parts irrelevant to 2.1]
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit b2e353e3c96eb81a721acba8df19ce8d198dae50)
[wt: drop FCGI changes]
Signed-off-by: Willy Tarreau <w@1wt.eu>
1 file changed