Create Header Anchor link from Russian

[zloyAltr]

• [x ] I confirm that this is an issue rather than a question.

Bug report

Incorrect conversion of Russian character when creating links

Steps to reproduce

1. I setting ## Единый каталог регистрации in my markdown document
2. The link is automatically created
3. This link is #единый-катаnог-регистрации
4. The russian symbol л (л) convert into symbol n (n)

What is expected?

What is actually happening?

Other relevant information

• My VuePress version is lower and euqal than 1.0.0-alpha.47:

  • VuePress version: 1.0.0-alpha.47
  • OS: Win7
  • Node.js version: 10
  • Browser version: Chrome 75.0.3770.80
  • Is this a global or local install? locall
  • Which package manager did you use for the install? npm
  • Does this issue occur when all plugins are disabled?

• My VuePress version is higher than 1.0.0-alpha.47, the following is the output of npx vuepress info in my VuePress project:

[osipxd]

It should be fixed with #1855 when it will be merged.