Fix egg metadata error

[Archmonger]

The current instructions in the readme regarding alternative installation methods states to use pip install -e git+https://github.com/jazzband/django-silk.git#egg=silk. However, this is incorrect and will result in the following error:

Obtaining silk from git+https://github.com/jazzband/django-silk.git#egg=silk
  Cloning https://github.com/jazzband/django-silk.git to c:\users\username\repositories\conreq\.venv\src\silk
  Running command git clone -q https://github.com/jazzband/django-silk.git 'c:\users\username\repositories\conreq\.venv\src\silk'
  WARNING: Generating metadata for package silk produced metadata for project name django-silk. Fix your #egg=silk fragments.
WARNING: Discarding git+https://github.com/jazzband/django-silk.git#egg=silk. Requested django-silk from git+https://github.com/jazzband/django-silk.git#egg=silk has inconsistent name: filename has 'silk', but metadata has 'django-silk'
ERROR: Could not find a version that satisfies the requirement silk (unavailable) (from versions: none)
ERROR: No matching distribution found for silk (unavailable)

This PR changes the instructions to use pip install -e git+https://github.com/jazzband/django-silk.git#egg=django-silk

[codecov]

Codecov Report

Merging #485 (6df4718) into master (7e93d6c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #485   +/-   ##
=======================================
  Coverage   82.83%   82.83%           
=======================================
  Files          50       50           
  Lines        2051     2051           
=======================================
  Hits         1699     1699           
  Misses        352      352           

Impacted Files	Coverage Δ
silk/urls.py
silk/__init__.py
project/project/urls.py	100.00% <0.00%> (ø)
project/project/__init__.py	60.00% <0.00%> (ø)

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[tiltec]

Test failures are definitely unrelated to changes in this PR, so this seems good to go.

I just became a Jazzband member to merge this PR ;) It's actually quite easy!