Fix typo in rebase explanation in commit-on-wrong-branch kata

[AngeloThys]

The kata states

rebase quickfix on master

When it should state: rebase master on quickfix.

---

Example code

git rebase quickfix master

When rebasing, you replay the commits of the second argument -master- onto the first argument -quickfix-, therefor, it is only correct to state that master should be rebased on quickfix.

To go from

%%{init: { 'logLevel': 'debug', 'theme': 'base', 'gitGraph': {'mainBranchName': 'remote', 'mainBranchOrder': 2}}}%%
gitGraph
    commit id: "A"
    branch master order: 1
    commit id: "B"
    checkout remote
    branch quickfix order: 3
    commit id: "C"

To

%%{init: { 'logLevel': 'debug', 'theme': 'base', 'gitGraph': {'mainBranchName': 'remote', 'mainBranchOrder': 2}}}%%
gitGraph
    commit id: "A"
    branch quickfix order: 3
    commit id: "C"
    branch master order: 1
    commit id: "B"