fix grammatical error in CONTRIBUTING.md

CONTRIBUTING.md

@@ -1,95 +1,95 b''
 ## Triaging Issues
 
 On the IPython repository,  we strive to trust users and give them responsibility.
 By using one of our bots, any user can close issues or add/remove
 labels by mentioning the bot and asking it to do things on your behalf.
 
 To close an issue (or PR), even if you did not create it, use the following:
 
 > @meeseeksdev close
 
 This command can be in the middle of another comment, but must start on its
 own line. 
 
 To add labels to an issue, ask the bot to `tag` with a comma-separated list of
 tags to add:
 
 > @meeseeksdev tag windows, documentation
 
 Only already pre-created tags can be added.  So far, the list is limited to:
 `async/await`, `backported`, `help wanted`, `documentation`, `notebook`,
 `tab-completion`, `windows`
 
 To remove a label, use the `untag` command:
 
 > @meeseeksdev untag windows, documentation
 
 We'll be adding additional capabilities for the bot and will share them here
 when they are ready to be used.
 
 ## Opening an Issue
 
 When opening a new Issue, please take the following steps:
 
 1. Search GitHub and/or Google for your issue to avoid duplicate reports.
    Keyword searches for your error messages are most helpful.
 2. If possible, try updating to master and reproducing your issue,
    because we may have already fixed it.
 3. Try to include a minimal reproducible test case.
 4. Include relevant system information.  Start with the output of:
 
         python -c "import IPython; print(IPython.sys_info())"
 
    And include any relevant package versions, depending on the issue, such as
    matplotlib, numpy, Qt, Qt bindings (PyQt/PySide), tornado, web browser, etc.
 
 ## Pull Requests
 
 Some guidelines on contributing to IPython:
 
 * All work is submitted via Pull Requests.
 * Pull Requests can be submitted as soon as there is code worth discussing.
   Pull Requests track the branch, so you can continue to work after the PR is submitted.
   Review and discussion can begin well before the work is complete,
   and the more discussion the better.
   The worst case is that the PR is closed.
 * Pull Requests should generally be made against master
 * Pull Requests should be tested, if feasible:
     - bugfixes should include regression tests.
     - new behavior should at least get minimal exercise.
 * New features and backwards-incompatible changes should be documented by adding
   a new file to the [pr](docs/source/whatsnew/pr) directory, see [the README.md
   there](docs/source/whatsnew/pr/README.md) for details.
 * Don't make 'cleanup' pull requests just to change code style.
   We don't follow any style guide strictly, and we consider formatting changes
   unnecessary noise.
   If you're making functional changes, you can clean up the specific pieces of
   code you're working on.
 
 [Travis](http://travis-ci.org/#!/ipython/ipython) does a pretty good job testing
 IPython and Pull Requests, but it may make sense to manually perform tests,
 particularly for PRs that affect `IPython.parallel` or Windows.
 
 For more detailed information, see our [GitHub Workflow](https://github.com/ipython/ipython/wiki/Dev:-GitHub-workflow).
 
 ## Running Tests
 
-All the tests can by running
+All the tests can be run by using
 ```shell
 iptest
 ```
 
 All the tests for a single module (for example **test_alias**) can be run by using the fully qualified path to the module.
 ```shell
 iptest IPython.core.tests.test_alias
 ```
 
 Only a single test (for example **test_alias_lifecycle**) within a single file can be run by adding the specific test after a `:` at the end:
 ```shell
 iptest IPython.core.tests.test_alias:test_alias_lifecycle
 ```
 
 For convenience, the full path to a file can often be used instead of the module path on unix systems. For example we can run all the tests by using
 ```shell
 iptest IPython/core/tests/test_alias.py
 ```