Fix extracting of org from org/repo name in workflow generating docs

Previously we've used `dest_org=${${{ inputs.destinationRepo }}%%/*}` which was
removing the longest part (separated by `/`) from the input. This wasn't what we
wanted in cases where the org name is longer than the repo name.
We're now changing the approach and we're using `dest_org=$(echo
${{ inputs.destinationRepo }} | cut -d'/' -f1)` command now. The `cut` command
is used to extract sections from lines of files or strings. In this case, we're
using it to split the ${{ inputs.destinationRepo }} string on the `/` delimiter
and then selecting the first field (`-f1`) before the delimiter.
By using this approach, it doesn't matter if the first or second part is longer;
it will always extract the first part of the variable containing `/`.

.github/workflows/reusable-solidity-docs.yml

@@ -253,7 +253,7 @@ jobs:
  echo "▶ Push commit"
  git push --set-upstream origin HEAD:$head_branch
  echo "▶ Check if PR for the head branch already exists"
-  dest_org=${${{ inputs.destinationRepo }}%%/*}
+ dest_org=$(echo ${{ inputs.destinationRepo }} | cut -d'/' -f1)
  pr_for_head=$(curl -L \
  -H "Accept: application/vnd.github+json" \
  -H "Authorization: Bearer $API_TOKEN_GITHUB" \