Spelling corrections for doc directory

Spelling corrections as found by codespell and in #561.

Some reported problems were already fixed, others are fixed here.
Theer are a few that are not corrected as they signal a documentation correction.

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/htmlcmds.doc b/doc/htmlcmds.doc
index 605bf5a..57ddf6f 100644
--- a/doc/htmlcmds.doc
+++ b/doc/htmlcmds.doc
@@ -304,7 +304,7 @@ The list of entities with their descriptions has been taken from <a href="http:/
 <li><tt>\&notin;</tt>`&nbsp;&nbsp;&nbsp;`                 not an element of: &notin;
 <li><tt>\&ni;</tt>`&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;`  contains as member: &ni;
 <li><tt>\&prod;</tt>`&nbsp;&nbsp;&nbsp;&nbsp;`            n-ary product = product sign: &prod;
-<li><tt>\&sum;</tt>`&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;`       n-ary sumation: &sum;
+<li><tt>\&sum;</tt>`&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;`       n-ary summation: &sum;
 <li><tt>\&minus;</tt>`&nbsp;&nbsp;&nbsp;`                 minus sign: &minus;
 <li><tt>\&lowast;</tt>`&nbsp;&nbsp;`                      asterisk operator: &lowast;
 <li><tt>\&radic;</tt>`&nbsp;&nbsp;&nbsp;`                 square root = radical sign: &radic;