Adding brew link workaround to known issues document

cli/known-issues.md

@@ -25,7 +25,20 @@ sudo port upgrade openssl
 sudo port -f uninstall openssl @0.9.8
 ```
 
-You can verify whether you have the right version using the  `openssl version` command from the Terminal. 
+You can verify whether you have the right version using the  `openssl version` command from the Terminal.
+
+## Problems using `brew` to link `openssl` after uprading
+Some users have reported problems when using `brew link --force openssl` command to link the upgraded OpenSSL. The error reported is a variation of the below:
+
+```console
+Linking /usr/local/Cellar/openssl/1.0.2h_1... 
+Error: Could not symlink share/man/man5/config.5ssl /usr/local/share/man/man5 is not writable
+```
+
+This is due to permissions being set in a certain way on the `/usr` directory on El Capitan. In order to workaround this problem, you need to give your user ownership of the directory and its contents. More information can be found on the following links:
+
+* http://blog.blakesimpson.co.uk/read/89-fix-homebrew-error-usr-local-bin-is-not-writable-on-os-x-el-capitan
+* http://stackoverflow.com/questions/26647412/homebrew-could-not-symlink-usr-local-bin-is-not-writable
 
 ## Running .NET Core CLI on Nano Server