Added hledger-mcp to the Community Servers

[iiAtlas]

Description

Adds hledger-mcp too the Community Servers section of the README.md

Motivation and Context

HLedger is a really cool plain-text accounting tool which I've been using for some time. It has been actively used and maintained since 2007! The "source" is text files, written in double entry format. As an example, here are two entries:

2023-01-05 Grocery Store
  expenses:food                           $85.50
  assets:bank:checking                   -$85.50

2023-01-10 Coffee Shop
  expenses:dining:coffee                  $4.75
  assets:cash                            -$4.75

Users typically interface with hledger through the hledger cli. A powerful tool, with a steep learning curve. This MCP exposes comprehensive access to the cli commands, but through a nice LLM interface. It has --read-only mode to prevent writing to your data, if desired.

How Has This Been Tested?

I've been using this locally for a few weeks now and iterating on it. You can view a demo here if desired: https://github.com/iiAtlas/hledger-mcp/blob/main/images/spend-demo.gif

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context