Proposing a PR to fix a few small typos

[timgates42]

Issue Type

[x] Bug (Typo)

Steps to Replicate and Expected Behaviour

• Examine gpxpy/gpx.py and observe containint, however expect to see containing.
• Examine gpxpy/gpx.py and observe specificed, however expect to see specified.
• Examine CONTRIBUTING.md and observe inssue, however expect to see issue.
• Examine README.md and observe acess, however expect to see access.

Notes

Semi-automated issue generated by
https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md

To avoid wasting CI processing resources a branch with the fix has been
prepared but a pull request has not yet been created. A pull request fixing
the issue can be prepared from the link below, feel free to create it or
request @timgates42 create the PR. Alternatively if the fix is undesired please
close the issue with a small comment about the reasoning.

https://github.com/timgates42/gpxpy/pull/new/bugfix_typos

Thanks.

[tkrajina]

Sorry for the late reply and.. Yes, those fixes make perfect sense. Feel free to send a PR.

[timgates42]

Thanks @tkrajina added #239