docs: minor typo fixes in docs (#2068)

Signed-off-by: Daniel J. Dufour <[email protected]>

Author: DanielJDufour

CONTRIBUTING.md

@@ -116,7 +116,7 @@ pre-commit install
 - In order to commit to this repository, please read and accept our
   [commit sign-off policy](https://developercertificate.org)
 - This is simply to verify that you are the author of the commits you make.
-- If possible, please add to your commit footer the `Signed-of-by` info:
+- If possible, please add to your commit footer the `Signed-off-by` info:
   `Signed-off-by: John Doe <[email protected]>`
 
 ## Our Development Practices

README.md

@@ -63,7 +63,7 @@ the FMTM aims to solve the problem of **coordinating** field mapping campaigns.
 This project relies heavily on the [ODK](getodk.org) ecosystem underneath:
 
 - [XLSForms](https://xlsform.org) are used for the underlying data collection
-  survey. The fields in this survey can be mapped to OpenStreeMap tags.
+  survey. The fields in this survey can be mapped to OpenStreetMap tags.
 - [ODK Central](https://github.com/getodk/central) is used to store the XLSForm
   and receive data submissions from users.
 - [ODK Collect](https://github.com/getodk/collect) is a mobile app that the user