Spelling corrections

A number of spelling corrections as reported by the codespell (see: https://github.com/codespell-project/codespell) program and lists.

Some remarks:
- not considered are grammatical errors
- not considered are names in the code although there are a number that could be improved (like `childs` -> `children`)
- in the documentation it could be made clearer what are variables and what is running text (e.g. by placing variables in running text between backticks)
- some comments are in the French language, I think it would be better to have them in the English (United States version).

1 files changed, 1 insertions, 1 deletions

diff --git a/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h b/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h
index d428e497..2301a66b 100644
--- a/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h
+++ b/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h
@@ -211,7 +211,7 @@ class Persistent_cohomology {
   /** \brief Update the cohomology groups under the insertion of an edge.
    *
    * The 0-homology is maintained with a simple Union-Find data structure, which
-   * explains the existance of a specific function of edge insertions. */
+   * explains the existence of a specific function of edge insertions. */
   void update_cohomology_groups_edge(Simplex_handle sigma) {
     Simplex_handle u, v;
     boost::tie(u, v) = cpx_->endpoints(sigma);