fixing typos and breaking link issues (envoyproxy#11270)

Signed-off-by: Abhay Narayan Katare <[email protected]>

Commit Message: Fixing breaking link issues and typos
Additional Description:
Risk Level: LOW
Testing: format and integration
Docs Changes:Yes
Release Notes:
[Optional Runtime guard:]
[Optional Fixes envoyproxy#11215
[Optional Deprecated:]

Author: ankatare

PULL_REQUESTS.md

@@ -70,7 +70,7 @@ to relevant parts of the documentation. Thank you! Please write in N/A if there
 ### <a name="runtime_guard"></a>Runtime guard
 
 If this PR has a user-visible behavioral change, or otherwise falls under the
-guidelines for runtime guarding in the [contributing doc](CONTRIBUTING.md.md)
+guidelines for runtime guarding in the [contributing doc](CONTRIBUTING.md)
 it should have a runtime guard, which should be documented both in the release
 notes and here in the PR description.
 

docs/root/start/sandboxes/fault_injection.rst

@@ -48,7 +48,7 @@ Terminal 2
   $ docker-compose exec envoy bash
   $ bash send_request.sh
 
-The script above (``send_request.sh``) sends a continuous stream of HTTP requests to Envoy, which in turn forwards the requests to the backend container. Fauilt injection is configured in Evoy but turned off (i.e. affects 0% of requests). Consequently, you should see a continuous sequence of HTTP 200 response codes.
+The script above (``send_request.sh``) sends a continuous stream of HTTP requests to Envoy, which in turn forwards the requests to the backend container. Fauilt injection is configured in Envoy but turned off (i.e. affects 0% of requests). Consequently, you should see a continuous sequence of HTTP 200 response codes.
 
 **Step 4: Test Envoy's abort fault injection**